CN102832832B - Low-power alternating current and direct current (AC-DC) power circuit - Google Patents
Low-power alternating current and direct current (AC-DC) power circuit Download PDFInfo
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- CN102832832B CN102832832B CN201210343564.6A CN201210343564A CN102832832B CN 102832832 B CN102832832 B CN 102832832B CN 201210343564 A CN201210343564 A CN 201210343564A CN 102832832 B CN102832832 B CN 102832832B
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Abstract
The invention discloses a low-power alternating current and direct current (AC-DC) power circuit. The low-power AC-DC power circuit comprises a filter circuit, a rectification circuit, a fixed cut-off pulse width modulation (PWM) controller, a compensation circuit of the fixed cut-off PWM controller and a Flyback converter main circuit, wherein the output of the filter circuit is connected to the rectification circuit; the output of the rectification circuit is connected to a main line; the fixed cut-off PWM controller samples a voltage signal on the main line and current flowing through a primary coil and controls the cut-off time through the compensation circuit to drive a power tube; and the compensation circuit samples the voltage signal from the main line and outputs the voltage signal to the fixed cut-off PWM controller. By fully utilizing the characteristic of simplicity of the compensation circuit of the fixed cut-off PWM controller, the low-power AC-DC power circuit guarantees that dead zone time in each switching period exists, so that the whole system is maintained in a direct current main (DCM) mode and can work stably. Compared with the conventional low-power AC-DC power circuit on the market, the low-power AC-DC power circuit has the advantages of simple structure, low cost, high power factor, high reliability, high cost performance and the like.
Description
Technical field
The present invention relates to a kind of small-power AC-DC power circuit with power factor emendation function, particularly there is the system works of maintaining at the compensating circuit of DCM pattern.
Background technology
Along with becoming increasingly conspicuous of global energy crisis, " green energy resource " is rooted in the hearts of the people." green energy resource " not only requires power consumption equipment energy conversion efficiency high but also require power factor high, avoids electric network pollution.
Small-power AC-DC power circuit is widely used in household electrical appliance, office equipment.Although the IEC61000-3-2 harmonic content standard of European Union has cogent provision small power LED illumination driving power, need to not there is power factor emendation function, when a large amount of low-power LED illuminating lamps are applied, can cause electric network pollution simultaneously yet.Therefore, for small-power AC-DC power circuit, still need to have power factor emendation function.
The application system of actual AC-DC power circuit often has the otherwise requirements such as cost, installation, as low-power LED room lighting driving power, is faced with and should guaranteeing lighting quality, the difficult problem reducing costs again.For small-power AC-DC power circuit, if adopt complicated circuit of power factor correction to improve power factor, can cause cost to increase, be difficult to apply.Also some application, as being arranged on the drive circuit in cup-shaped LED lamp holder, volume requirement is very harsh.
In sum, existing small-power AC-DC power circuit power factor is low, even if having power factor emendation function, its power factor and stability neither be very desirable, and structure is also comparatively complicated, causes cost higher.And if design inverse excitation type converter be operated under DCM pattern, if under actual conditions without special control circuit, it will enter into CCM pattern.Adopt after the technical scheme of following summary of the invention part, will overcome the problems referred to above, can make simultaneously small-power AC-DC power circuit have simple in structure, cost is low, power factor is high, reliability is high, cost performance advantages of higher.
Summary of the invention
Technical problem to be solved by this invention is to provide the small-power AC-DC power circuit with power factor emendation function, the application has improved the power factor of existing small-power AC-DC power circuit, reduce volume, reduced cost, improved reliability and cost performance.Meanwhile, the present invention takes full advantage of the simple feature of compensating circuit of the fixing PWM of shutoff controller, guarantees that Dead Time exists in each switch periods, makes whole system maintain DCM pattern, thereby stably works.Compare with the existing small-power AC-DC power circuit in market, that the present invention has is simple in structure, cost is low, power factor is high, reliability is high, cost performance advantages of higher.
The present invention is by adopting following technical proposals to realize:
A kind of small-power AC-DC power circuit, it is characterized in that: comprise filter circuit, rectification circuit, the fixing PWM of shutoff controller, fixing compensating circuit and the Flyback inverter main circuit that turn-offs PWM controller, rectification circuit is received in the output of described filter circuit; The output access main line of rectification circuit; The fixing PWM controller that turn-offs is sampled to the voltage signal on main line and the electric current that flows through primary coil; The fixing compensating circuit that turn-offs PWM controller gathers voltage signal from main line, and the fixing PWM of shutoff controller is received in output, and the fixing PWM of shutoff controller carrys out driving power pipe in conjunction with the fixing compensating circuit that turn-offs PWM controller to the control of turn-off time.
Described filter circuit is conventional filter circuit.
Described rectification circuit is conventional rectification circuit.
Described fixing shutoff PWM controller is prior art.
Described Flyback inverter main circuit is custom circuit.
The compensating circuit of described fixing shutoff PWM controller comprises a diode D1, six resistance-be respectively R1, R2, R3, R4, R5 and R6, two electric capacity-be respectively C1 and C2, n type field effect transistor M1 and two p type field effect transistors-be respectively M2 and M3, annexation is: the sinusoidal input voltage signal of half-wave after R1 mono-termination rectification
v in , another termination R2; A termination R1 of R2, other end ground connection; The node that R1, R2 are connected and the anode of D1 join, and the negative electrode of D1 is connected with the grid of M1; The grid of M1 is connected to one end of R3 and C1 simultaneously, and R3 is in parallel with C1, the other end ground connection of R3 and C1; The source electrode of M1 connects one end of R4, the other end ground connection of R4; The drain electrode of M1 connects the drain electrode of M2; The drain electrode of a termination M2 of R5, one end of another termination C2 of R5, joins with the turn-off time control end of PWM controller simultaneously, the other end ground connection of C2; The source electrode of M2 connects feeder ear
, the grid of M2 connects the grid of M3; The source electrode of M3 connects feeder ear
, the grid of M3 and drain electrode short circuit, the drain electrode of M3 connects one end of R6, the other end ground connection of R6.
Compared with prior art, the technique effect that the present invention reaches is as follows:
One, in the present invention, the small-power AC-DC power circuit that adopts " filter circuit, rectification circuit, the fixing PWM of shutoff controller; fixing compensating circuit and the Flyback inverter main circuit that turn-offs PWM controller " to be connected to form, has thoroughly solved that existing small-power AC-DC power circuit power factor is low, volume is large, cost is high, reliability and the low problem of cost performance.Meanwhile, the present invention takes full advantage of the simple feature of compensating circuit of the fixing PWM of shutoff controller, guarantees that Dead Time exists in each switch periods, makes whole system maintain DCM pattern, thereby stably works.Compare with the existing small-power AC-DC power circuit in market, that the present invention has is simple in structure, cost is low, power factor is high, reliability is high, cost performance advantages of higher.
Two,, in the present invention, the concrete structure of the compensating circuit of the fixing shutoff of employing PWM controller respectively tool has the following advantages:
1, the sampling of the input voltage signal after utilizing sample circuit to rectification, voltage V1 through D1, R3, C1 output and sampled signal homophase, the grid of voltage V1 access n type field effect transistor M1, thus make the electric current that flows through M1 there is identical variation tendency with sampled signal;
2, p type field effect transistor M2, M3 and resistance R 6 form current source, electric current is provided to the branch road of resistance R 5 and capacitor C 2 compositions and the branch road of n type field effect transistor M1 and resistance R 4 compositions, when flowing through the electric current increase of M1, the charged electrical of capacitor C 2 is failed to be convened for lack of a quorum and reduced, vice versa, thereby make electric current and V1 that C2 is charged anti-phase, when the voltage on C2 reaches the reference voltage in the fixing PWM of shutoff controller, the output voltage of driving power tube grid is from low transition to high level, power tube is opened, finally make the variation tendency in charging interval of C2 identical with V1, the input voltage of the turn-off time of having realized power tube after along with rectification has identical variation tendency.
3, the fixing compensating circuit that turn-offs PWM controller, by simple circuit, guarantees the existence of Dead Time, makes whole system maintain DCM pattern.
Accompanying drawing explanation
Below in conjunction with specification drawings and specific embodiments, the present invention is described in further detail, wherein:
Fig. 1 is AC-DC power circuit block diagram of the present invention, has summarized briefly composition structure of the present invention.The present invention is electric main at input voltage, and output voltage is the direct voltage of tens ~ tens volts.
Fig. 2 is the voltage on main line and current waveform after rectification.
Fig. 3 is the compensating circuit of the fixing PWM of shutoff controller.
Embodiment
Embodiment 1
As a better embodiment of the present invention, the invention discloses a kind of small-power AC-DC power circuit, comprise filter circuit, rectification circuit, the fixing PWM of shutoff controller, fixing compensating circuit and the Flyback inverter main circuit that turn-offs PWM controller.Rectification circuit is received in the output of filter circuit of the present invention, the output access main line of rectification circuit.The fixing PWM controller that turn-offs is sampled to the voltage signal on main line and the electric current that flows through primary coil, in conjunction with its compensating circuit, the control of turn-off time is carried out to driving power pipe simultaneously.Compensating circuit gathers voltage signal from main line, and the fixing PWM of shutoff controller is received in output.Described filter circuit is conventional filter circuit.Described rectification circuit is conventional rectification circuit.Described fixing shutoff PWM controller is prior art.Described Flyback inverter main circuit is custom circuit.
Embodiment 2
For the switching power circuit of inverse-excitation type, when it has power factor emendation function, the envelope of the current peak after rectification is half-wave sinusoidal waveform, and phase approximation is consistent with the half-wave voltage waveform after rectification.The sinusoidal input voltage of half-wave after rectification
0 ~ pi/2 half period, the peak value of the input current of each switch periods increases gradually, because the voltage at primary coil two ends also increases gradually, curent change slope also increases thereupon, according to
Known, in each switch periods, the time of Current rise is approximate constant.Pi/2 ~ π half period of the sinusoidal input voltage of half-wave after rectification, the peak value of the input current of each switch periods reduces gradually, because the voltage at primary coil two ends also reduces gradually, curent change slope also reduces thereupon, and in each switch periods, the time of Current rise is still approximate constant.
While being operated in DCM pattern according to converter, for making magnetic core not depart from its magnetic hysteresis loop, must equate by assurance number of positive and negative weber of transformer,
In formula,
for the voltage at primary coil two ends in each switch periods,
for the power tube opening time,
for secondary output voltage,
for the primary coil number of turn,
for the secondary coil number of turn,
be the resetting time of transformer, secondary current reduced to for zero required time.
When
along with the sinusoidal input voltage of the half-wave after rectification
during increase,
constant, the value on the equation left side increases, and
for output voltage, must remain unchanged, therefore, for equation is set up,
can increase.When
be greater than the power tube turn-off time
(under DCM pattern
,
for Dead Time) time, system can enter CCM pattern by the DCM pattern arranging, and causes system works unstable.Therefore, the small-power AC-DC power circuit for power factor emendation function, is operated in DCM pattern in order to ensure it, need to the turn-off time of power tube, finely tune according to the variation of the sinusoidal input voltage of the half-wave after rectification, to maintain
existence, anti-locking system enters CCM pattern.
As preferred forms of the present invention, it is comprised of filter circuit, rectification circuit, the fixing PWM controller and compensating circuit and Flyback inverter main circuit thereof of turn-offing, and it is characterized in that:
Adopt Flyback to convert main topological structure, in conjunction with fixing PWM controller and the compensating circuit thereof of turn-offing, realize the efficient stable work of system.
After filter circuit of the present invention and rectification circuit are processed the civil power of input, access main line.The fixing PWM controller that turn-offs is sampled to the voltage signal on main line and the electric current that flows through primary coil, in conjunction with its compensating circuit, the control of turn-off time is carried out to driving power pipe simultaneously.
The compensating circuit of fixing shutoff PWM controller of the present invention is by diode D1, resistance R 1, R2, R3, R4, R5, R6, capacitor C 1, C2, and n type field effect transistor M1 and p type field effect transistor M2, M3 form.The sinusoidal input voltage signal of half-wave after R1 mono-termination rectification
v in , another termination R2, a termination R1 of R2, other end ground connection; The node that R1, R2 are connected and the anode of D1 join, and the negative electrode of D1 is connected with the grid of M1.The grid of M1 is connected to one end of R3 and C1 simultaneously, and R3 is in parallel with C1, their other end ground connection; The source electrode of M1 connects one end of R4, the other end ground connection of R4; The drain electrode of M1 connects the drain electrode of M2.One end of R5 also connects the drain electrode of M2, and one end of another termination C2 of R5 joins with the turn-off time control end of PWM controller simultaneously, the other end ground connection of C2.The source electrode of M2 connects feeder ear
, the grid of M2 connects the grid of M3, and the source electrode of M3 connects feeder ear
, the grid of M3 and drain electrode short circuit, the drain electrode of M3 connects one end of R6, the other end ground connection of R6.The compensating circuit of described fixing shutoff PWM controller, the input voltage signal sampling after utilizing sample circuit to rectification, the voltage V1 through D1, R3, C1 output with sampled signal homophase.The grid of voltage V1 access n type field effect transistor M1, thus make the electric current that flows through M1 there is identical variation tendency with sampled signal.P type field effect transistor M2, M3 and resistance R 6 form current source, electric current are provided to the branch road of resistance R 5 and capacitor C 2 compositions and the branch road of n type field effect transistor M1 and resistance R 4 compositions.When flowing through the electric current increase of M1, the charged electrical of capacitor C 2 is failed to be convened for lack of a quorum and reduced, vice versa.Thereby make electric current and V1 that C2 is charged anti-phase.When the voltage on C2 reaches the reference voltage in the fixing PWM of shutoff controller, the output voltage of driving power tube grid is from low transition to high level, and power tube is opened.Finally make the variation tendency in charging interval of C2 identical with V1, the input voltage of the turn-off time of having realized power tube after along with rectification has identical variation tendency.The compensating circuit of described fixing shutoff PWM controller, by simple circuit, guarantees the existence of Dead Time, makes whole system maintain DCM pattern.
Embodiment 3
Be below another better embodiment of the present invention, the present invention is comprised of filter circuit, rectification circuit, fixing shutoff PWM controller and compensating circuit thereof, Flyback inverter main circuit.The fixing compensating circuit that turn-offs PWM controller is realized whole circuit and is maintained DCM pattern, to reach the target of system stability work.
Filter circuit and rectification circuit form voltage after the civil power of input is processed
.Fixing shutoff PWM controller and compensating circuit thereof are according to right
sampling and the sampling of flowing through the electric current of primary coil, carry out driving power pipe.
Voltage signal in the fixing compensating circuit that turn-offs PWM controller after R1 mono-termination rectification, the other end ground connection of connecting with R2, generation voltage division signal.Voltage division signal on the anode access R2 of D1, negative electrode is connected with the grid of M1.The grid of M1 is connected to one end of R3 and C1 simultaneously, and R3 is in parallel with C1, and other end ground connection forms filter circuit jointly, and sampled signal is carried out after filtering, and the electric current of M1 can following sampling signal intensity.By the grid of M3 and drain electrode short circuit, ground connection after connecting with R6, forms current source simultaneously.M2 and M3 form current mirror, the branch road that the branch road that the current mirror that M3 and R6 are produced forms to resistance R 5 and capacitor C 2 and n type field effect transistor M1 and resistance R 4 form.The electric current that flows through the branch road that resistance R 5 and capacitor C 2 form is contrary, contrary with the variation tendency of sampled signal with the variation tendency of electric current that flows through M1.And electric current is larger, shorter to the charging interval of electric capacity, thus make the charging interval of electric capacity identical with the variation tendency of sampled signal, the variation tendency of the turn-off time of power tube is identical with the variation tendency of input voltage after rectification.The above element forms the compensating circuit of the fixing PWM of shutoff controller, realizes whole circuit and maintains DCM pattern, to reach the target of system stability work.
Claims (1)
1. a small-power AC-DC power circuit, it is characterized in that: comprise filter circuit, rectification circuit, the fixing PWM of shutoff controller, fixing compensating circuit and the Flyback inverter main circuit that turn-offs PWM controller, rectification circuit is received in the output of described filter circuit; The output access main line of rectification circuit; The fixing PWM controller that turn-offs is sampled to the voltage signal on main line and the electric current that flows through primary coil; The fixing compensating circuit that turn-offs PWM controller gathers voltage signal from main line, and the fixing PWM of shutoff controller is received in output, and the fixing PWM of shutoff controller carrys out driving power pipe in conjunction with the fixing compensating circuit that turn-offs PWM controller to the control of turn-off time;
The compensating circuit of described fixing shutoff PWM controller comprises a diode D1, six resistance-be respectively R1, R2, R3, R4, R5 and R6, two electric capacity-be respectively C1 and C2, n type field effect transistor M1 and two p type field effect transistors-be respectively M2 and M3, annexation is: the sinusoidal input voltage signal of half-wave after R1 mono-termination rectification
v in , another termination R2; A termination R1 of R2, other end ground connection; The node that R1, R2 are connected and the anode of D1 join, and the negative electrode of D1 is connected with the grid of M1; The grid of M1 is connected to one end of R3 and C1 simultaneously, and R3 is in parallel with C1, the other end ground connection of R3 and C1; The source electrode of M1 connects one end of R4, the other end ground connection of R4; The drain electrode of M1 connects the drain electrode of M2; The drain electrode of a termination M2 of R5, one end of another termination C2 of R5, joins with the turn-off time control end of PWM controller simultaneously, the other end ground connection of C2; The source electrode of M2 connects feeder ear
, the grid of M2 connects the grid of M3; The source electrode of M3 connects feeder ear
, the grid of M3 and drain electrode short circuit, the drain electrode of M3 connects one end of R6, the other end ground connection of R6.
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|---|---|---|---|
| CN201210343564.6A CN102832832B (en) | 2012-09-17 | 2012-09-17 | Low-power alternating current and direct current (AC-DC) power circuit |
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| CN201210343564.6A CN102832832B (en) | 2012-09-17 | 2012-09-17 | Low-power alternating current and direct current (AC-DC) power circuit |
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| CN102832832B true CN102832832B (en) | 2014-08-13 |
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Family Cites Families (1)
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| ITMI20031315A1 (en) * | 2003-06-27 | 2004-12-28 | St Microelectronics Srl | DEVICE FOR CORRECTION OF THE POWER FACTOR IN FORCED SWITCHING POWER SUPPLIES. |
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Patent Citations (4)
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| CN101506752A (en) * | 2006-08-07 | 2009-08-12 | 意法半导体股份有限公司 | Fixed-off-time power factor correction controller |
| CN102195292A (en) * | 2010-03-12 | 2011-09-21 | 联咏科技股份有限公司 | Power factor correcting device |
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