CN107196528B - The control method and control circuit of switching power unit - Google Patents
The control method and control circuit of switching power unit Download PDFInfo
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- CN107196528B CN107196528B CN201610146359.9A CN201610146359A CN107196528B CN 107196528 B CN107196528 B CN 107196528B CN 201610146359 A CN201610146359 A CN 201610146359A CN 107196528 B CN107196528 B CN 107196528B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
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- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The application provides the control circuit and control method of a kind of switching power unit, for controlling the switch element in switching power unit, the control circuit includes: to disconnect moment control unit, is used to control the disconnection of the switch element according to the voltage difference between reference voltage and the output DC voltage；Zero current detection unit is used to detect at the time of to flow through the electric current of inductor be zero；Frequency limit unit generates limitation signal according to time constant adjustment signal, during the limitation signal is used to set the delay from the switch element disconnects the moment, wherein the size of the time constant adjustment signal changes over time；Turn-on instant control unit, the limitation signal of the testing result for being used to be exported according to the zero current detection unit and frequency limit unit output, controls the conducting of the switch element.According to the application, input current can be avoided to be distorted with simple circuit.
Description
Technical field
The present invention relates to power technique fields more particularly to the control methods and control circuit of a kind of switching power unit.
Background technique
Currently, PFC electricity can be installed additional mostly on switching power unit in order to improve the utilization efficiency of power supply
Road (Power Factor Corrector, PFC), to form switch power supply equipment.
Circuit of power factor correction common in the art includes critical conduction mode circuit of power factor correction (Critical
Mode PFC) and continuous conduction mode circuit of power factor correction (Continue Conduction Mode PFC).With facing
The switch power supply equipment of boundary's mode power factor correcting circuit at runtime, has following problems: along with the reduction of load, opening
The conducting of pass and the frequency of disconnection increase, so that switching loss increases.
In patent document 1 (Japan Patent 3070598, power-factor improvement converter), switching losses increase in order to prevent
Add, minimum switch periods are set so as to will not be connected again during switch element upon opening certain, is i.e. setting switch
Highest frequency inhibits the rising of switching frequency when light load as a result,.
Fig. 5 is a circuit structure diagram of the switch power supply equipment of patent document 1, includes switch in the switch power supply equipment
Power supply device and control circuit, Fig. 6 are the working timing figures of the switch power supply equipment of patent document 1.Such as Fig. 5, shown in Fig. 6,
T60 moment, zero current detection unit 501 detect that the electric current for flowing through inductor is zero and exports high level pulse signal, so that
"AND" circuit U1 also exports high level pulse signal, thus the Q terminal output high level letter of FF1 to the S terminal of trigger FF1
Number, which be connected switch element Q1 by switch element driver circuit, also, the height electricity of "AND" circuit U1 output
Switch element Q3 is connected instantaneously in flat pulse signal, and capacitor C4 is made to discharge, and then, switch element Q3 is backed off, capacitor C4
It is charged by current source I2；At the T61 moment, the output voltage of error amplifier A1 is less than the voltage of capacitor C3, therefore, from comparator
CP1 exports high level signal to the R terminal of trigger FF1, resets to trigger FF1, keeps the Q terminal of trigger FF1 defeated
Low level signal out, switch element Q1 is disconnected as a result,；In moment T63, the voltage of capacitor C4 is more than fixed voltage Vth, comparator
The limitation signal of CP2 output becomes high level；In moment T64, zero current detection unit 501 detects zero current again and exports
High level pulse signal, therefore, S terminal input high level pulse signal of the "AND" circuit U1 to trigger FF1, switch element Q1
It is connected again.
As it can be seen that in patent document 1, during T61-T63, the limitation signal of comparator CP2 output is low level, because
This can not be such that switch element Q1 is connected when T62 moment zero current detection unit 501 detects zero current, so, switch
It is delayed by the time of element conductive, thus, it is possible to inhibit the rising of switching frequency.
In patent document 2 (Japanese Unexamined Patent Publication 2014-82924, switching power unit), detection is input to switching power unit
Alternating voltage period, and detect load condition, in the case where light-load state, be controlled such that leading for switch element
Logical moment delay, to prevent switching frequency from rising, also, makes the delay of the turn-on instant on the same period of input voltage
It measures constant.
Patent document 1: Japan Patent 3070598, power-factor improvement converter
Patent document 2: Japanese Unexamined Patent Publication 2014-82924, switching power unit
It should be noted that the above description of the technical background be intended merely to it is convenient to the technical solution of the application carry out it is clear,
Complete explanation, and facilitate the understanding of those skilled in the art and illustrate.Cannot merely because these schemes the application's
Background technology part is expounded and thinks that above-mentioned technical proposal is known to those skilled in the art.
Summary of the invention
As described above, there are following properties by critical conduction mode PFC, the peak value of the low region inductor current of instantaneous voltage is inputted
Low, electric current becomes zero in the short time after switch element disconnection, thus carries out conducting next time, so, input instantaneous voltage
Switching frequency is got higher when low.
Therefore, in patent document 1, the rising of switching frequency when light load is limited by limitation maximum frequency of oscillation
To realize the improvement of switching losses.But after the upper limit of switching frequency is arranged, the low region of input instantaneous voltage is accessible to out
The upper limit of frequency is closed, is reduced so on-off times are compared in the region high with input instantaneous voltage.As a result, low in input instantaneous voltage
Region input current be difficult to flow, the input current in the high region of input instantaneous voltage increases, so as to cause power factor
Deteriorate；Also, when inputting instantaneous voltage below some value, since the upper limit of switching frequency is fixed value, input current waveform
Discontinuous variation sometimes, so as to cause input distortion.
Fig. 7 is the input voltage of the switch power supply equipment of patent document 1 and the correspondence diagram of input current.Such as figure
Shown in 7, when switch power supply equipment is converted to the switch motion of fixed highest frequency from the switch motion of critical conduction mode, input current
Waveform discontinuous variation occurs.
Patent document 2 proposes the solution of the above problem for patent document 1, and patent document 2 carries out following
Movement: detection load condition determines the retardation of the conducting timing of switch element, according to the load condition detected to reduce
Switching frequency, and the retardation is maintained within the exchange input half period.
As a result, above-mentioned power factor will not occur due to maintaining the retardation within the exchange input half period
Deterioration and input current waveform input distortion.
But patent document 2 but needs the detection circuit of load condition, determines the delay of turn-on instant according to load condition
Retardation within the circuit of amount, the detection circuit in input AC period and half period for maintaining the input AC period
Constant circuit, so, there are problems that circuit complicated.
According to the one aspect of the embodiment of the present application, provide a kind of for leading to the switch element in switching power unit
On and off drives the control circuit and control method of row control into, which carrys out configuration switch member using the time constant of variation
The timing period of the turn-on instant of part, as a result, in the case where instantaneous voltage reduces, switching frequency is divided at the time of reaching the upper limit
It dissipates, to prevent input current from discontinuously changing, input current distortion and the improvement of power factor is realized with simple circuit.
According to the one aspect of the embodiment of the present application, a kind of control circuit is provided, for opening in switching power unit
The conducting and disconnection for closing element are controlled, and the switching power unit includes:
Rectification unit, the ac voltage rectifier for the AC power source for being used to input are DC voltage；
Inductor is connect with the rectification unit；
Switch element is connected with the inductor, in the switching elements conductive, the switch element with it is described whole
The current path via the inductor is formed between current circuit；And
Diode is connect with the inductor, when the switch element disconnects, in the inductor and output capacitance
Between form the current path via the diode, also, generate scheduled output DC voltage at the output capacitance both ends；
The control circuit includes:
Moment control unit is disconnected, is used for according to the voltage difference control between reference voltage and the output DC voltage
The disconnection of the switch element；
Zero current detection unit is used to detect at the time of to flow through the electric current of the inductor be zero；
Frequency limit unit generates limitation signal according to time constant adjustment signal, and the limitation signal is for setting
During delay from the switch element disconnects the moment, wherein the size of the time constant adjustment signal changes over time；
And
Turn-on instant control unit is used for the testing result and the frequency exported according to the zero current detection unit
The limitation signal of limiting unit output, controls the conducting of the switch element.
According to the other side of the embodiment of the present application, wherein the frequency limit unit includes:
Current source；
Capacitor is charged by the current source；And
The voltage value of the capacitor is compared, according to comparison result by comparator with the voltage value of reference signal
Exporting the limitation signal, wherein the time constant adjustment signal is used to adjust the voltage value of the reference signal, and/or
Adjust the current value that the current source charges to the capacitor.
According to the other side of the embodiment of the present application, wherein the control circuit further include:
Counter divides the signal of the control switching elements conductive of turn-on instant control unit output,
To generate digital signal；And
Digital analog converter, the digital signal that the counter is exported are converted to analog signal, and by the mould
Intend signal as the time constant adjustment signal.
According to the other side of the embodiment of the present application, wherein the control circuit further include:
Oscillating circuit is used to export the oscillator signal changed over time, and using the oscillator signal as the time
Constant adjustment signal.
According to the other side of the embodiment of the present application, wherein the turn-on instant control unit is first from the switch
Part disconnects from the moment after during the delay, flows through the electric current of the inductor when the zero current detection unit detects
When being zero, make the switching elements conductive.
According to the other side of the embodiment of the present application, wherein the inductor of the zero current detection unit detection
Electric current at the time of refer to that electric current decays to zero from the value greater than zero at the time of be zero.
According to the other side of the embodiment of the present application, wherein the week that the time constant adjustment signal changes over time
Phase is less than the half in the period of the alternating voltage.
According to the one aspect of the embodiment of the present application, a kind of control method is provided, for opening in switching power unit
The conducting and disconnection for closing element are controlled, which includes:
The disconnection of the switch element is controlled according to the voltage difference between reference voltage and the output DC voltage；
Detection is at the time of to flow through the electric current of the inductor be zero；
Limitation signal is generated according to time constant adjustment signal, the limitation signal is disconnected from the switch element for setting
During opening the delay risen constantly, wherein the size of the time constant adjustment signal changes over time；And
According to the electric current is zero at the time of testing result and the limitation signal, control leading for the switch element
It is logical.
The beneficial effects of the present invention are: so that switching frequency when instantaneous voltage reduces is divided at the time of reaching the upper limit
It dissipates, to prevent input current from discontinuously changing, realizes input current distortion and the improvement of power factor.
Referring to following description and accompanying drawings, only certain exemplary embodiments of this invention is disclosed in detail, specifies original of the invention
Reason can be in a manner of adopted.It should be understood that embodiments of the present invention are not so limited in range.In appended power
In the range of the spirit and terms that benefit requires, embodiments of the present invention include many changes, modifications and are equal.
The feature for describing and/or showing for a kind of embodiment can be in a manner of same or similar one or more
It uses in a other embodiment, is combined with the feature in other embodiment, or the feature in substitution other embodiment.
It should be emphasized that term "comprises/comprising" refers to the presence of feature, one integral piece, step or component when using herein, but simultaneously
It is not excluded for the presence or additional of one or more other features, one integral piece, step or component.
Detailed description of the invention
Included attached drawing is used to provide to be further understood from the embodiment of the present invention, and which constitute one of specification
Point, for illustrating embodiments of the present invention, and come together to illustrate the principle of the present invention with verbal description.Under it should be evident that
Attached drawing in the description of face is only some embodiments of the present invention, for those of ordinary skill in the art, is not paying wound
Under the premise of the property made is laborious, it is also possible to obtain other drawings based on these drawings.In the accompanying drawings:
Fig. 1 is a circuit structure diagram of the switch power supply equipment of embodiment 1；
Fig. 2 is another circuit structure diagram of the switch power supply equipment of embodiment 1；
Fig. 3 is a circuit structure diagram of the switch power supply equipment of embodiment 2；
Fig. 4 is a working timing figure of the switch power supply equipment of embodiment 2；
Fig. 5 is a circuit structure diagram of the switch power supply equipment of patent document 1；
Fig. 6 is a working timing figure of the switch power supply equipment of patent document 1；
Fig. 7 is the input voltage of the switch power supply equipment of patent document 1 and a correspondence diagram of input current；
Fig. 8 is the input voltage of the switch power supply equipment of embodiment 1 and a correspondence diagram of input current；
Fig. 9 is the input voltage of the switch power supply equipment of embodiment 1 and another correspondence diagram of input current；
Figure 10 is a flow chart of the control method of embodiment 3.
Specific embodiment
Referring to attached drawing, by following specification, aforementioned and other feature of the invention be will be apparent.In specification
In attached drawing, only certain exemplary embodiments of this invention is specifically disclosed, which show the portions that can wherein use principle of the invention
Divide embodiment, it will thus be appreciated that the present invention is not limited to described embodiments, on the contrary, the present invention includes falling into appended power
Whole modifications, modification and equivalent in the range of benefit requirement.
Embodiment 1
The embodiment of the present application 1 provides a kind of control circuit, for the switch element in switching power unit conducting and
Disconnection is controlled, wherein the switching power unit and the control circuit constitute switch power supply equipment.
Fig. 1 is a circuit structure diagram of the switch power supply equipment of the present embodiment 1.As shown in Figure 1, the switch power supply equipment
1 include switching power unit 10 and control circuit 20, wherein switching power unit 10 include rectification unit 101, inductor 102,
Switch element 103 and diode 104, control circuit 20 include disconnect moment control unit 201, zero current detection unit 202,
Frequency limit unit 203 and turn-on instant control unit 204.
As shown in Figure 1, in switching power unit 10, the alternating current for the AC power source that rectification unit 101 is used to input
Pressure is rectified into DC voltage；Inductor 102 is connect with rectification unit 101；Switch element 103 is connected with inductor 102, is being switched
The current path via inductor 102 is formed when element 103 is connected, between switch element 103 and rectification circuit 101；Diode
104 connect with inductor 102, when switch element 103 disconnects, are formed between inductor 102 and output capacitance C1 via two
The current path of pole pipe 104, also, scheduled output DC voltage is generated at the both ends output capacitance C1.
As shown in Figure 1, disconnecting moment control unit 201 in control circuit 20 and being used for according to reference voltage and export straight
The disconnection of voltage difference control switch element 103 between galvanic electricity pressure；Zero current detection unit 202 flows through inductor for detecting
At the time of 102 electric current is zero；Frequency limit unit 203 generates limitation signal, limitation letter according to time constant adjustment signal
Number for set from switch element 103 disconnection the moment delay during, wherein the size of time constant adjustment signal is at any time
Variation；The testing result and frequency limit unit that turn-on instant control unit 204 is used to be exported according to zero current detection unit 202
The limitation signal of 203 outputs, the conducting of control switch element 103.
It, can be according to the time constant adjustment signal changed over time come configuration switch according to the control circuit of the present embodiment
The timing period of the turn-on instant of element, as a result, in the case where instantaneous voltage reduces, quilt at the time of switching frequency reaches the upper limit
Dispersion realizes the improvement of input current distortion and power factor with simple circuit to prevent input current from discontinuously changing.
Fig. 8 and Fig. 9 is the input voltage of the switch power supply equipment of embodiment 1 and a corresponding relationship of input current respectively
Schematic diagram, as shown in Figure 8, Figure 9, according to the control circuit of the application, switch power supply equipment, which can work, makes switch element
Under the changed mode of highest frequency, as a result, input current variation is smooth, input current distortion and power factor are realized
Improvement.
As shown in Figure 1, in the present embodiment, rectification unit 101 for example can be the bridge being made of multiple rectifier diodes
Formula rectifier.This implementation is not limited to this, and rectification unit 101 can also have other structures.Structure about rectification unit 101
The prior art can be referred to principle, this embodiment is not repeated.
In the present embodiment, switching power unit 10 can also have switch element driver circuit 105, which drives
Dynamic circuit 105 can receive the signal of the conducting of control switch element 103, and driving switch element 103 is connected.
The working principle of switching power unit 10 in this present embodiment is closed, the prior art can be referred to, the present embodiment is not
It is illustrated again.
As shown in Figure 1, disconnecting moment control unit 201 may include turn-on time control circuit 2011 and error amplification electricity
Road 2012, wherein the resistance R1 and R2 of switching power unit can carry out output DC voltage to voltage and divide, the error
Amplifier A1 in amplifying circuit 2012 can divide obtained voltage to resistance R1 and R2 to be compared with reference voltage Vref
Compared with according to comparison result come output error value of magnification；The mistake that turn-on time control circuit 2011 can be exported according to amplifier A1
Poor value of magnification, output control signal, which can be input into the RESET input R of trigger FF1, to determine to switch
The disconnection moment of element 103, thus the time of the conducting of control switch element 103, therefore, the disconnection moment of switch element 103
Or turn-on time can be the target value determined by R1, R2 and Vref.
In the present embodiment, as shown in Figure 1, turn-on time control circuit 2011 may include current source I1, comparator
CP1, capacitor C3 and switch Q2 etc., error amplifying circuit 2012 may include amplifier A1 and phase compensation capacitor C2, put
The non-inverting input of big device A1 is connected with reference voltage Vref.Certainly, the present embodiment is not limited to this, turn-on time control electricity
Road 2011 and error amplifying circuit 2012 can have other circuit structures.
In the present embodiment, zero current detection unit 202 can be connect with the auxiliary winding D being set in inductor 102,
The electric current proportional to inductor 102 can be generated in auxiliary winding D, therefore, zero current detection unit 202 is auxiliary by detecting
Help the electric current in winding D, so that it may which detection is at the time of to flow through the electric current of inductor 102 be zero.
In the present embodiment, in a critical period of the electric current for flowing through inductor, there are two electric current be zero at the time of,
At the time of what the zero current detection unit 202 detected is that the electric current decays to zero from the value greater than zero.Detecting that the electric current is
At the time of zero, which can export zero current detection signal, be used to indicate the beginning of a critical period
Or terminate, therefore, during which exports two adjacent detection signals, correspond to a critical week
Phase.Specific method at the time of electric current is zero is detected, the prior art can be referred to, this embodiment is not repeated.
In the present embodiment, frequency limit unit 203 can generate limitation signal, the limit according to time constant adjustment signal
During signal processed is used to set the delay from switch element 103 disconnects the moment, the switch of switch element 103 is determined as a result,
The upper limit of frequency.
In the present embodiment, frequency limit unit 203 can have for capacitor charging current source, capacitor and
Comparator is that the comparator can be compared according to the voltage value of capacitor with the voltage value of reference signal as a result, output limit
Signal processed.In the present embodiment, which can be used for adjusting the voltage value of the reference signal, and/or adjust
The current value that the whole current source charges to the capacitor.
In the present embodiment, the detection knot that turn-on instant control unit 204 can be exported according to zero current detection unit 202
The limitation signal that fruit and frequency limit unit 203 export, the turn-on instant of control switch element 103.For example, from switch element
103 disconnect from the moment after during above-mentioned delay, flow through the electric current of inductor 102 when zero current detection unit 202 detects
When being zero, switch element 103 is connected.
As shown in Figure 1, in the present embodiment, which may include "AND" circuit U1 and triggering
Device FF1.
Wherein, an input terminal of U1 can be connect with the output end of zero current detection unit 202, another input of U1
End can be connect with the output end of frequency limit unit 203, and the output end of U1 is connect with the setting input terminal S of trigger FF1.
The RESET input R of trigger FF1 can connect the output of the comparator CP1 in turn-on time control circuit 2011
End, the output end Q of trigger FF1 are connected to the grid of switch element 103, trigger FF1 via switch element driver circuit 105
Output endIt can connect the grid of the switch element Q2 in turn-on time control circuit 2011.The output end Q of trigger FF1
The signal that can be connected with output control switch element 103.
In the present embodiment, time constant adjustment signal can generate in control circuit 20.As shown in Figure 1, control electricity
Road 20 can also include counter 205 and digital analog converter 206.
Wherein, the letter that counter 205 can be connected the control switch element 103 that turn-on instant control unit 204 exports
It number is divided, to generate digital signal；The digital signal that counter 205 exports can be converted to mould by digital analog converter 206
Quasi- signal, and frequency limit unit 203 is input to using the analog signal as the time constant adjustment signal.
In the present embodiment, when the signal that each slave flipflop FF1 output control switch element 103 is connected, counter 205
The signal will be divided, generate the digital signal of 2 bits or other bits, the digital signal is by digital analog converter 206
Analog signal is converted to, which can be by as time constant adjustment signal.As it can be seen that slave flipflop FF1 output every time
When the signal that control switch element 103 is connected, the digital signal that counter 205 exports can all change, and lead to time constant tune
Entire signal variation, so that the upper limiting frequency of switch element 103 be made to change.
Certainly, the present embodiment is without being limited thereto, and control circuit 20 can also generate time constant tune using other circuits
Entire signal.
Fig. 2 is another circuit structure diagram of the switch power supply equipment of the present embodiment 1.The difference of Fig. 2 and Fig. 1 is in
In using the counter 205 and digital analog converter 206 of 207 alternate figures 1 of oscillating circuit in the control circuit of Fig. 2.
In Fig. 2, oscillating circuit 207 can export the oscillator signal changed over time, when which can be used as
Between constant adjustment signal be input into frequency limit unit 203, can also make to be determined most by time constant adjustment signal as a result,
High-frequency changes.
In addition, in the present embodiment, time constant adjustment signal can also be generated in the outside of control circuit 20 and quilt
It is input in control circuit 20.
In the present embodiment, the period that time constant adjustment signal changes over time can be less than the alternating voltage week of input
The half of phase, as a result, in the half period of alternating voltage, so that switching frequency reaches in the case where instantaneous voltage reduces
Dispersed at the time of the upper limit, to keep the variation of input current smooth, realizes input current distortion and the improvement of power factor.
Embodiment 2
The embodiment of the present application 2 provides a kind of control circuit, is a concrete implementation side of the control circuit of embodiment 1
Formula.In example 2, the structure of frequency limit unit 203 is described.Same as Example 1ly, the control of embodiment 2
Circuit and switching power unit constitute switch power supply equipment.
Fig. 3 is the circuit structure diagram of the switch power supply equipment of embodiment 2, is not repeated to illustrate with Fig. 1 something in common.Fig. 3
Difference with Fig. 1 is that Fig. 3 shows the composed structure of frequency limit unit 203.
As shown in figure 3, frequency limit unit 203 may include capacitor C4, switch Q3, comparator CP2 and current source I2,
Wherein, output end of the output end of comparator CP2 as frequency limit unit 203, and the inverting input terminal quilt of comparator CP2
Input time constant adjustment signal, the time constant adjustment signal can be the output signal of D/A converting circuit 206.
Fig. 4 is the timing diagram of the circuit of Fig. 3.In the following, illustrating the control circuit of the embodiment of the present application 2 in conjunction with Fig. 3, Fig. 4
Working principle.
Output voltage is divided by resistance R1 and R2, and is input in the inverting input terminal of amplifier A1；Amplifier A1
Normal phase input end be entered reference voltage Vref.
The output of amplifier A1 is connected with phase compensation capacitor C2, charges to capacitor C2.The output of amplifier A1 also with
The inverting input terminal of the comparator CP1 of turn-on time control unit 2011 connects.
During switch element 103 is connected, the output end of trigger FF1Export low level, turn-on time control unit
2011 switch Q2 is disconnected, and is charged by current source I1 to C3, and the voltage of C3 is ramp waveform shown in Fig. 4.
The output voltage of comparator CP1 comparison amplifier A1 and the voltage of C3, if unanimously, resetting trigger FF1, making
The end Q of trigger FF1 exports low level, thus during the conducting for terminating switch element 103, while Q2 is connected, made by Q2
C3 electric discharge.
By the action, the disconnection moment for disconnecting 201 control switch element 103 of moment control unit, so that output voltage
As the particular value determined by R1, R2, Vref.
The output of zero current detection unit 202 is connect with an input terminal of U1.
If the input of the other end of U1 is high level, through zero current detecting circuit 202 when detecting zero current
FF1 is arranged in the high level signal of output, and switch element 103 is connected.
In the biggish situation of critical period, when determining the conducting of switch element 103 by zero current detection unit 202
It carves, the disconnection moment of the disconnection of switch element 103 is determined by disconnecting moment control unit 201, the Switching Power Supply of Fig. 3 is set as a result,
It is standby to work under common critical conduction mode.
In the following, for during moment T0 to moment T3, to illustrate that switch power supply equipment work is changing most high frequency
Movement under rate mode.
It is entered high level signal at the end S of moment T0, FF1, the end Q of FF1 exports high level, switch element 103 as a result,
Conducting.Meanwhile the high level pulse of U1 output keeps switch Q3 conducting primary, C4 is discharged, and after the high level pulse, Q3 is disconnected
It opens, I2 charges to C4.Also, the high level signal of the Q terminal output of FF1 is digital signal by the frequency dividing of counter 205, and should
Digital signal is converted to analog signal by D/A converting circuit 206, and is input into the negative of CP2 as time constant adjustment signal
End.
In moment T1, the voltage of C3 is more than the output voltage of A1, and CP1 exports high level signal, and FF1 is reset, switch member
Part 103 disconnects.
In moment T2, the voltage of C4 charging is more than the voltage of time constant adjustment signal, and limitation signal becomes high level.Its
In, for during delay of the switch element 103 from disconnecting the moment, within this period, limitation signal is low electricity during T1-T2
It is flat, also, within this period, even if zero current detecting circuit 202 detects that zero current, U1 also continue to output low level signal,
So switch element 103 is not switched on.
In moment T3, zero current detecting circuit 202 detects zero current, and U1 exports high level signal, so switch element
103 are switched on, meanwhile, Q3 is switched on again, and C4 is made to discharge.Also, the high level signal of the Q terminal output of FF1 is by counter
205 frequency dividings are digital signal, and generate new time constant adjustment signal.
In the present embodiment, the time constant adjustment signal of moment T0 and moment T3 is not identical, that is to say, that the time is normal
Number adjustment signal time to time change, so that switching frequency is divided at the time of reaching the upper limit in the case where instantaneous voltage reduces
It dissipates, to keep the variation of input current smooth, realizes input current distortion and the improvement of power factor.
In addition, in the present embodiment, as shown in Fig. 2, counter 205 and digital analog converter 206 can be substituted and vibration is arranged
Circuit 207 is swung to generate variable time constant adjustment signal, as a result, the switch member determined by time constant adjustment signal
The upper limiting frequency of part 103 changes.Alternatively, the voltage of the reference signal of the negative terminal of CP2 can be fixed, and adjusted using time constant
Signal adjusts the charging current of current source I2, and the upper limiting frequency of switch element 103 can also changed.
Embodiment 3
The embodiment of the present application 3 provides a kind of control method of Switching Power Supply, the control circuit with embodiment 1 and embodiment 2
It is corresponding, for controlling the switch element in Fig. 1, Fig. 2 and Switching Power Supply shown in Fig. 3.
Figure 10 is a flow diagram of the control method of the present embodiment 3, as shown in Figure 10, this method comprises:
S1001, according to reference voltage and output DC voltage between voltage difference control switch element disconnection；
S1002, detection are at the time of to flow through the electric current of inductor be zero；
S1003, limitation signal is generated according to time constant adjustment signal, limitation signal is for setting from the switch element
During delay from the disconnection moment, wherein the size of the time constant adjustment signal changes over time；And
S1004, according to at the time of the electric current is zero testing result and the limitation signal, it is first to control the switch
The conducting of part.
In the present embodiment, refer at the time of the electric current of the inductor of step S1002 detection is zero the electric current from
At the time of value greater than zero decays to zero.
In the present embodiment, the period that time constant adjustment signal changes over time can be less than the one of AC voltage cycle
Half.
It, can be according to the time constant adjustment signal changed over time come configuration switch according to the control method of the present embodiment
The timing period of the turn-on instant of element, as a result, in the case where instantaneous voltage reduces, quilt at the time of switching frequency reaches the upper limit
Dispersion realizes the improvement of input current distortion and power factor to prevent input current from discontinuously changing.
Combine specific embodiment that the application is described above, it will be appreciated by those skilled in the art that this
A little descriptions are all exemplary, and are not the limitation to the application protection scope.Those skilled in the art can be according to the application
Spirit and principle various variants and modifications are made to the application, these variants and modifications are also within the scope of application.
Claims (8)
1. a kind of control circuit, for the switch element in switching power unit conducting and disconnection control,
The switching power unit includes:
Rectification unit, the ac voltage rectifier for the AC power source for being used to input are DC voltage；
Inductor, one end are connect with the positive polarity output terminal of the rectification unit；
Switch element, one end are connect with the other end of the inductor, and the other end of the switch element and the rectification are single
The negative polarity output connection of member, in the switching elements conductive, forms between the switch element and the rectification unit
Via the current path of the inductor；And
Diode is connect with the inductor, when the switch element disconnects, between the inductor and output capacitance
The current path via the diode is formed, also, generates scheduled output DC voltage at the output capacitance both ends；
The control circuit is characterized in that the control circuit includes:
Moment control unit is disconnected, is used for according to the voltage difference control between reference voltage and the output DC voltage
The disconnection of switch element；
Zero current detection unit is used to detect at the time of to flow through the electric current of the inductor be zero；
Frequency limit unit generates limitation signal according to time constant adjustment signal, and the limitation signal is for setting from institute
During stating the delay from switch element disconnects the moment, wherein the size of the time constant adjustment signal changes over time；And
Turn-on instant control unit, the testing result for being used to be exported according to the zero current detection unit and the frequency limit
The limitation signal of unit output, controls the conducting of the switch element.
2. control circuit as described in claim 1, which is characterized in that the frequency limit unit includes:
Current source；
Capacitor is charged by the current source；And
The voltage value of the capacitor is compared with the voltage value of reference signal, is exported according to comparison result by comparator
The limitation signal,
Wherein, the time constant adjustment signal is used to adjust the voltage value of the reference signal, and/or the adjustment current source
The current value to charge to the capacitor.
3. control circuit as described in claim 1, which is characterized in that the control circuit further include:
Counter divides the signal of the control switching elements conductive of turn-on instant control unit output, with life
At digital signal；And
Digital analog converter, the digital signal that the counter is exported is converted to analog signal, and the simulation is believed
Number be used as the time constant adjustment signal.
4. control circuit as described in claim 1, which is characterized in that the control circuit further include:
Oscillating circuit is used to export the oscillator signal changed over time, and using the oscillator signal as the time constant
Adjustment signal.
5. control circuit as described in claim 1, which is characterized in that
The turn-on instant control unit from the switch element disconnect the moment after during the delay, when described zero
When current detecting unit detects that flowing through the electric current of the inductor is zero, make the switching elements conductive.
6. control circuit as described in claim 1, which is characterized in that
The electric current of the inductor of the zero current detection unit detection refers to that electric current declines from the value greater than zero at the time of being zero
At the time of being kept to zero.
7. control circuit as described in claim 1, which is characterized in that
The period that the time constant adjustment signal changes over time is less than the half in the period of the alternating voltage.
8. a kind of control method, for the switch element in switching power unit conducting and disconnection control,
The switching power unit includes:
Rectification unit, the ac voltage rectifier for the AC power source for being used to input are DC voltage；
Inductor, one end are connect with the positive polarity output terminal of the rectification unit；
Switch element, one end are connect with the other end of the inductor, and the other end of the switch element and the rectification are single
The negative polarity output connection of member, in the switching elements conductive, forms between the switch element and the rectification unit
Via the current path of the inductor；And
Diode is connect with the inductor, when the switch element disconnects, between the inductor and output capacitance
The current path via the diode is formed, also, generates scheduled output DC voltage at the output capacitance both ends；
The control method is characterized in that the control method includes:
The disconnection of the switch element is controlled according to the voltage difference between reference voltage and the output DC voltage；
Detection is at the time of to flow through the electric current of the inductor be zero；
Limitation signal is generated according to time constant adjustment signal, when the limitation signal is disconnected for setting from the switch element
During the delay carved, wherein the size of the time constant adjustment signal changes over time；And
According to the electric current is zero at the time of testing result and the limitation signal, control the conducting of the switch element.
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| CN201610146359.9A CN107196528B (en) | 2016-03-15 | 2016-03-15 | The control method and control circuit of switching power unit |
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|---|---|---|---|
| CN201610146359.9A CN107196528B (en) | 2016-03-15 | 2016-03-15 | The control method and control circuit of switching power unit |
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| CN107196528B true CN107196528B (en) | 2019-05-14 |
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| US10673385B2 (en) * | 2017-11-08 | 2020-06-02 | Mediatek Inc. | Supply modulator, modulated power supply circuit, and associated control method |
| JP6898882B2 (en) * | 2018-04-09 | 2021-07-07 | 株式会社Ｓｏｋｅｎ | Power converter control device |
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|---|---|---|---|---|
| WO2009025517A2 (en) * | 2007-08-22 | 2009-02-26 | Silicon Mitus, Inc. | Power factor correction circuit |
| CN102263492A (en) * | 2010-05-28 | 2011-11-30 | 瑞萨电子株式会社 | Semiconductor device and power supply device |
| CN103683918A (en) * | 2012-09-25 | 2014-03-26 | 富士电机株式会社 | Switching power supply |
| JP2014233110A (en) * | 2013-05-28 | 2014-12-11 | ルネサスエレクトロニクス株式会社 | Power factor improvement circuit |
| CN105281556A (en) * | 2014-07-15 | 2016-01-27 | 意法半导体股份有限公司 | Control circuit implementing method for controlling switching power factor corrector, PFC and AC/DC converter |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100904299B1 (en) * | 2008-11-03 | 2009-06-25 | 주식회사 실리콘마이터스 | Power factor compensation circuit and driving metod thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009025517A2 (en) * | 2007-08-22 | 2009-02-26 | Silicon Mitus, Inc. | Power factor correction circuit |
| CN102263492A (en) * | 2010-05-28 | 2011-11-30 | 瑞萨电子株式会社 | Semiconductor device and power supply device |
| CN103683918A (en) * | 2012-09-25 | 2014-03-26 | 富士电机株式会社 | Switching power supply |
| JP2014233110A (en) * | 2013-05-28 | 2014-12-11 | ルネサスエレクトロニクス株式会社 | Power factor improvement circuit |
| CN105281556A (en) * | 2014-07-15 | 2016-01-27 | 意法半导体股份有限公司 | Control circuit implementing method for controlling switching power factor corrector, PFC and AC/DC converter |
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