CN102215000A - Isolated primary circuit regulator - Google Patents
Isolated primary circuit regulator Download PDFInfo
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- CN102215000A CN102215000A CN2010101457213A CN201010145721A CN102215000A CN 102215000 A CN102215000 A CN 102215000A CN 2010101457213 A CN2010101457213 A CN 2010101457213A CN 201010145721 A CN201010145721 A CN 201010145721A CN 102215000 A CN102215000 A CN 102215000A
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Abstract
The invention discloses an isolated primary circuit regulator, which is applicable to a primary side of a transformer of a power supply. The isolated primary circuit regulator outputs a switching signal and can switch the transformer by the switching signal to further achieve an effect of stabilizing an output current. The isolated primary circuit regulator comprises a discharging time detector, an oscillator, a pulse width regulator and a control circuit, wherein the discharging time detector can be used for detecting the discharging time of a switching current which is generated on a secondary side of the transformer; the oscillator can be used for generating an oscillation signal; the control circuit can be used for outputting an adjustment signal; the pulse width regulator can output the switching signal according to the oscillation signal which is output by the oscillator and the adjustment signal which is output by the control circuit; and an operating period and a frequency of the switching signal correspond to the operating periods and the frequencies of the oscillation signal and the adjustment signal.
Description
Technical field
The present invention relates to a kind of isolated primary circuit adjuster, particularly a kind of isolated primary circuit adjuster with control circuit.
Background technology
Present electronic installation, in order to meet the demand of security regulations, power supply unit must provide regulated output voltage and stable output current.With this understanding, power supply unit is most likely in conjunction with transformer, and at the primary side of transformer the suitching type adjuster is set and adjusts output current.Yet, in the design field of present disclosed related transformer, the technology of suitching type adjuster is set at the primary side of transformer, still can't very accurately control the output current of power supply unit.Therefore, the designer must increase current circuit by the secondary side at power supply unit again, to reach the current curve of deciding with linear characteristic.In the case, cost of manufacture increases significantly.Therefore, both how reaching and can reduce cost, and can accurately control the output current of power supply unit again, is the problem of a worth research in fact.
At present the way that the suitching type adjuster is adjusted the output current of power supply unit is set, it is characterized in that to obtain the discharge time of a primary side switched voltage signal and a secondary side switch current by primary side at transformer.Wherein, primary side switched voltage signal results from the primary side of transformer, and the secondary side switch current results from the secondary side of transformer.Correlation technique can be with reference to TaiWan, China patent I277852 number with research, this patent disclosure a kind of suitching type adjuster, in order to the output current of control power supply unit.This suitching type regulator applications is in the primary side of a transformer of a power supply unit.This suitching type adjuster comprises a wave mode detector that produces current waveform signal, in order to detect Circuit Fault on Secondary Transformer switch current discharge time one discharge time detector, in order to produce oscillator signal and to control an oscillator of the switching frequency of switching signal, in order to integration one average current signal and discharge time and produce an integrator of an integrated signal, in order to amplifying integrated signal and an error amplifier of output current control loop be provided, and according to a comparator of the pulse bandwidth of this switching signal of output may command of this error amplifier.The disclosed technological means of this patent utilizes an electric current to detect end, directly detects a primary side switched voltage signal of the primary side of the transformer that results from power supply unit.Though but output current that it should be noted that power supply unit can obtain stable the adjustment by this technical characterictic,, and make this suitching type adjuster cause erroneous judgement easily because of switch switches the problem that moment causes the voltage spring.In addition, integrator, wave mode detector all increase the cost of manufacture of this suitching type adjuster.
Summary of the invention
Technical problem to be solved by this invention provides a kind of isolated primary circuit adjuster that solves above-mentioned existing in prior technology problem, is applied to a primary side of a transformer of a power supply unit.
To achieve these goals, the invention provides a kind of isolated primary circuit adjuster, be applied to a primary side of a transformer, wherein, comprising:
One discharge time detector, connect this transformer, this, detector resulted from a discharge time of switching electric current of a secondary side of this transformer in order to detection discharge time, this, detector was exported a discharge time signal and an anti-discharge time signal discharge time;
One oscillator is in order to produce an oscillator signal;
One control circuit, this control circuit connects this of detector discharge time, and in order to reach this anti-discharge time signal according to this discharge time signal, to a critical voltage carry out that output current wave remakes, filtering, amplification and signal processing relatively, signal is adjusted in this control circuit output one, wherein, this critical voltage switches the peak value of voltage signal corresponding to one of this primary side that results from this transformer, and;
One pulse width modulation device, this pulse width modulation device comprises a first input end and one second input, wherein this first input end connects this control circuit, this second input connects this oscillator, signal is switched in this pulse width modulation device output one, wherein, the work period of this switching signal and frequency are adjusted signal corresponding to this oscillator signal and this, and this adjustment signal is in order to this pulse wave width modulation device of resetting.
Above-mentioned isolated primary circuit adjuster, wherein, this switched voltage signal is the current signal that magnetizes.
Above-mentioned isolated primary circuit adjuster, wherein, this control circuit comprises:
One output current wave remakes circuit, in order to according to this discharge time signal, this anti-discharge time signal, this switching signal and this critical voltage, export a square-wave signal, wherein, the amplitude of this square-wave signal is corresponding to this critical voltage, the time of occurrence of this square-wave signal and this discharge time signal are synchronous, and the waveform of this square-wave signal is corresponding to the waveform of an output current;
One low pass filter is in order to filter this square-wave signal to export a direct current signal;
One difference amplifier becomes this critical voltage in order to amplify this direct current signal; And
One comparator is connected between this difference amplifier and this pulse width modulation device, this comparator in order to relatively this critical voltage and this switched voltage signal to produce this adjustment signal.
Above-mentioned isolated primary circuit adjuster, wherein, this output current wave remakes circuit and comprises:
One first switch, the input of this first switch connects this critical voltage, and this first switch is controlled by this switching signal;
One second switch is series at this first switch, and this second switch is controlled by this discharge time signal;
One the 3rd switch connects this second switch, and is parallel to this first switch and this second switch, and the 3rd switch is controlled by this anti-discharge time signal;
One first electric capacity is connected to the contact of this first switch and this second switch, and this first electric capacity is in order to store this critical voltage; And
One buffer is connected to the contact of this second switch and the 3rd switch, and this buffer is in order to buffering and export this square-wave signal.
Above-mentioned isolated primary circuit adjuster, wherein, this low pass filter comprises:
One first resistance is connected this output current wave and remakes between circuit and this difference amplifier, and this first resistance is in order to receive this square-wave signal; And
One second electric capacity is connected to the contact of this first resistance and this difference amplifier, and this second electric capacity is in order to the HFS of this square-wave signal of filtering.
The isolated primary circuit adjuster of this kind comprises: one discharge time detector, an oscillator, a pulse width modulation device and a control circuit.
Discharge time, detector connected transformer.Discharge time detector can in order to detection result from transformer a secondary side one switch the discharge time of electric current, and export a discharge time signal and an anti-discharge time signal.
The input of control circuit connects detector discharge time, and can be in order to according to discharge time signal and anti-discharge time signal, to a critical voltage carry out that output current wave remakes, filtering, amplification, with the signal processing of comparison.Control circuit can be adjusted signal in order to export one.Wherein, critical voltage can be the peak value of a switching voltage signal of the primary side that results from transformer.
Oscillator can be in order to produce an oscillator signal.
The first input end of pulse width modulation device is connected control circuit and oscillator respectively with second input.The pulse width modulation device can be adjusted signal and oscillator signal in order to receive, and exports a switching signal according to this.Wherein, the work period of switching signal and frequency are corresponding to oscillator signal and adjustment signal, and the adjustment signal can be in order to replacement pulse wave width modulation device.
Technique effect of the present invention is: can and can stablize the output current of adjusting power supply unit by the switching signal switching transformer according to isolated primary circuit adjuster of the present invention.In addition, isolated primary circuit adjuster according to the present invention also adopts control circuit to replace existing wave mode detector and integrator.Therefore, isolated primary circuit adjuster according to the present invention is not the switched voltage signal of the direct detection primary side that results from transformer, but utilizes the back coupling design of control circuit, obtains equivalent critical voltage indirectly.Isolated primary circuit adjuster according to the present invention not only can be stablized the output current of adjusting power supply unit, also can avoid switching because of switch the problem of the voltage spring that moment causes.
Describe the present invention below in conjunction with the drawings and specific embodiments, but not as a limitation of the invention.
Description of drawings
Fig. 1 is arranged at the schematic diagram of power supply unit for the isolated primary circuit adjuster of the present invention;
Fig. 2 is the schematic diagram of isolated according to an embodiment of the invention primary circuit adjuster;
Fig. 3 is the each point signal waveforms in power supply unit when operation of Fig. 1;
Fig. 4 A is the schematic diagram of pulse width modulation device according to an embodiment of the invention;
Fig. 4 B is the each point signal waveforms of pulse width modulation device according to an embodiment of the invention;
Fig. 5 remakes the schematic diagram of circuit for output current wave according to an embodiment of the invention;
Fig. 6 is the schematic diagram of low pass filter according to an embodiment of the invention;
Fig. 7 is the each point signal waveforms of control circuit according to an embodiment of the invention.
Wherein, Reference numeral
10 transformers
20 isolated primary circuit adjusters
22 discharge time detector
24 oscillators
26 pulse width modulation devices
28 control circuits
30 transistors
40 auxiliary resistances
41 SR type flip-flops
42 gate pole drivers
50 rectifiers
60 electric capacity
70 rectifiers
100 output current waves remake circuit
101 first switches
102 second switches
103 the 3rd switches
104 first electric capacity
105 buffers
200 low pass filters
201 first resistance
202 second electric capacity
300 difference amplifiers
400 comparators
N
AAuxiliary winding
N
PFirst side winding
N
SSecondary side winding
R
SDetect resistance
V
oOutput voltage
V
InInput voltage
I
oOutput current
I
PThe primary side switch current
I
PkPrimary side switch current maximum
I
sThe secondary side switch current
I
SpkSecondary side switch current maximum
V
CsPrimary side switched voltage signal
t
OnThe high levle time interval
t
DiscDischarge time
t
DisfThe low level time interval
The T cycle
The PLS oscillator signal
The VDD power source supply end
The GND earth terminal
The VOUT output
VDET test side discharge time
The VS switched voltage detects end
V
gFirst test side
V
fSecond test side
V
PWMSwitching signal
V
WReflected voltage
V
eCritical voltage
V
ModAdjust signal
V
DisDischarge time signal
V
DisBAnti-discharge time signal
V
A 'Buffering signals
V
aSquare-wave signal
V
bDirect current signal
V
RefReference voltage
Embodiment
Below in conjunction with accompanying drawing structural principle of the present invention and operation principle are done concrete description:
Please refer to Fig. 1, be arranged at the schematic diagram of power supply unit for the isolated primary circuit adjuster 20 of one embodiment of the invention.
Isolated primary circuit adjuster 20 can be applicable to a primary side of a transformer 10 of a power supply unit.Power supply unit has an output voltage V
o, output current I
oWith input voltage V
In
Power supply unit comprises transformer 10, and transformer 10 has auxiliary winding N
A, first side winding N
PWith secondary side winding N
S
Wherein, primary side is defined as commonly in input voltage V
InA side of earth terminal, and secondary side is defined as commonly in output voltage V
oThe opposite side of earth terminal.
Isolated primary circuit adjuster 20 comprise power source supply end VDD, earth terminal GND, output VOUT, discharge time test side VDET and switched voltage detect end VS.
Power source supply end VDD connects an end of electric capacity 60, and the other end ground connection of electric capacity 60.And power source supply end VDD sees through rectifier 50 with the contact of electric capacity 60 and is connected auxiliary winding N
A
Earth terminal GND ground connection.
Output VOUT connects transistor 30.
Discharge time, test side VDET saw through the auxiliary winding N of auxiliary resistance 40 connections
A
Switched voltage detects end VS between transistor 30 and detection resistance R S.In other words, switched voltage detects the contact that end VS connects transistor 30 and detects resistance R S.Wherein, detect resistance R
SArrive ground connection in order to the source electrode that connects transistor 30.
Isolated primary circuit adjuster 20 can see through test side VDET detection of reflected voltage V discharge time
W, reach through switched voltage and detect the primary side switched voltage signal V of end VS detection corresponding to the primary side switch current IP that primary side produced of transformer
Cs, with foundation reflected voltage V
WWith primary side switched voltage signal V
CsProduce one and switch signal V
PWM, and export the switching signal V of generation via its output VOUT
PWM
In this, isolated primary circuit adjuster 20 can utilize switching signal V
PWMSwitching transistor 30 is with the change action of control transformer 10.
Wherein, primary side switched voltage signal V
CsCan be the current signal that magnetizes.Reflected voltage V
WCan see through rectifier 50 can further charge to electric capacity 60, to cause reflected voltage V
WCan provide energy to isolated primary circuit adjuster 20 by this.
As switching signal V
PWMDuring for high levle, transistor 30 is switched on, and transistor 30 produces primary side switch current IP.And as switching signal V
PWMWhen switching to low level, the energy that is stored in transformer 10 can be released to the secondary side of transformer 10, and this energy can see through the output that a rectifier 70 is transferred to power supply unit.
When transistor 30 was switched on, transistor 30 can produce primary side switch current IP at the primary side of transformer.Primary side switch current IP can be via detecting resistance R
STransfer primary side switched voltage signal V to
Cs, and switched voltage detect the end VS can detect this primary side switched voltage signal V
CsWherein, primary side switch current IP can increase along with the time of transistor 30 conductings, and reached primary side switch current maximum I
Pk
Primary side switched voltage signal V
CsMagnitude of voltage also can be along with time of transistor 30 conductings increases, and reach critical voltage V
eWherein, critical voltage V
eBe primary side switched voltage signal V
CsPeak value.Wherein, detect resistance R
SCan be fixed resistance value, and critical voltage V
eWith primary side switch current maximum I
PkCan be directly proportional, it concerns suc as formula (1).
V
e＝I
pk*R
S ---------------------------------------------------------(1)
See also Fig. 2, the inside of isolated primary circuit adjuster 20 is provided with and can comprises: one discharge time detector 22, an oscillator 24, a pulse width modulation device 26 and a control circuit 28.
Discharge time, detector 22 input connected test side VDET discharge time.Discharge time, detector 22 output connected an input of control circuit 28.
The first input end of pulse width modulation device 26 is connected control circuit 28 and oscillator 24 respectively with second input.Pulse width modulation device 26 can be in order to output switching signal V
PWMAnd switching signal V
PWMCan connect transistor 30 via output VOUT.
Discharge time, detector 22 was through test side VDET detection of reflected voltage V discharge time
W, discharge time signal V is provided according to this
DisWith anti-discharge time signal V
DisBGive control circuit 28.Wherein, discharge time signal V
DisWith anti-discharge time signal V
DisBPhase place is opposite.
Please cooperate and consult Fig. 3, in this discharge process, can be formed with secondary side switch current I at the secondary side of transformer
s, and can form response secondary side switch current I in the primary side of transformer
sReflected voltage V
WWherein, as switching signal V
PWMWhen just being switched to low level, secondary side switch current I
sHas secondary side switch current maximum I
SpkAnd as secondary side switch current I
sAlong with discharge process reduces gradually, and secondary side switch current I
sWhen finally being returned to zero, reflected voltage V
WThen rapid drawdown immediately.
Wherein, secondary side switch current maximum I
SpkWith primary side switch current maximum I
PkCan be directly proportional, its relational expression is suc as formula (2).
I
spk＝I
pk*N
P/N
S --------------------------------------------(2)
Fig. 3 is for testing the oscillogram that is measured according to an embodiment of the invention.As can be seen from Figure 3, secondary side switch current I
sT discharge time
Disc, can adaptive switched signal V
PWMThe time point that is switched to low level is to secondary side switch current I
sThe time point of complete obiteration calculates.
Because discharge time, detector 22 can detect secondary side switch current I via test side VDET discharge time
s(receive reflected voltage V
W), so discharge time, detector 22 can be by calculating switching signal V
PWMThe time point that is switched to low level is to secondary side switch current I
sThe time point of complete obiteration obtains secondary side switch current I
sT discharge time
DiscHereat, discharge time, detector 22 can effectively detect t discharge time
Disc
One input connection detector discharge time 22 of control circuit 28.Control circuit 28 is annexation by this, can receive corresponding to t discharge time
DiscDischarge time signal V
DisWith anti-discharge time signal V
DisBAnd control circuit 28 can be according to switching signal V
PWM, discharge time signal V
Dis, anti-discharge time signal V
DisB, to critical voltage V
eCarry out that output current wave remakes, filtering, amplification, with signal processing relatively, use output and adjust signal V
Mod
Pulse width modulation device 26 can receive adjustment signal V from control circuit 28 respectively via its first and second input
ModWith oscillator signal PLS from oscillator 24.
Please refer to Fig. 4 A, pulse width modulation device 26 comprises a SR type flip-flop (SR flip flop) 41 and one gate pole driver (Gate Drive) 42.
Shown in Fig. 4 B, oscillator signal PLS can be in order to decision switching signal V
PWMWhen be switched to high levle; Adjust signal V
ModCan be in order to decision switching signal V
PWMWhen be switched to low level.
According to the control circuit 28 of one embodiment of the invention, as shown in Figure 2, comprise that output current wave remakes circuit 100, low pass filter 200, difference amplifier 300 and comparator 400.
Output current wave remakes circuit 100 in order to according to switching signal V
PWM, discharge time signal V
DisWith anti-discharge time signal V
DisB, to critical voltage V
eIntercept value preserving to remake the output current I of secondary side
oTwo times amount, and with after the corresponding coefficient correction, final output current wave remakes circuit 100 outputs one square-wave signal V
a
Square-wave signal V wherein
aAmplitude corresponding to critical voltage V
e, square-wave signal V
aTime of occurrence and discharge time signal V
DisSynchronously, and square-wave signal V
aWaveform can be corresponding to output current I
oWaveform.
The negative input end of difference amplifier 300 connects direct current signal V
bThe positive input terminal of difference amplifier 300 connects a reference voltage V
RefDifference amplifier 300 is according to direct current signal V
bWith reference voltage V
RefCan be in order to amplifying its difference, and difference amplifier 300 output critical voltage V
eWherein, reference voltage V
RefValue can be corresponding to output current I
oFor example: as output current I
oBe 0.7 ampere-hour, reference voltage V
RefCan be set to 0.7 volt.
At this, the critical voltage V of difference amplifier 300 outputs
eThe input that remakes circuit 100 to output current wave capable of feedback.Back coupling mechanism by this, output current wave remake circuit 100 and can obtain equivalent in primary side switched voltage signal V
CsVoltage and decision to switch the position accurate, thereby the shake that can reduce because of switch moment causes the erroneous judgement of suitching type adjuster.
According to one embodiment of the invention, see also Fig. 5, output current wave remakes circuit 100 and comprises one first switch 101, a second switch 102, one the 3rd switch 103, one first electric capacity 104 and a buffer 105.
Then, please cooperate and consult Fig. 3.As switching signal V
PWMDuring for high levle, transistor 30 is switched on, and transistor 30 produces primary side switch current IP, at this moment secondary side switch current I
sDo not form as yet.Still define: switching signal V
PWMFor the time interval of high levle is high levle time interval t
OnAt high levle time interval t
OnIn, switching signal V
PWMBe high levle, discharge time signal V
DisBe low level, anti-discharge time signal V
DisBBe high levle.
Then, through high levle time interval t
OnAfter, switching signal V
PWMThe energy that originally was stored in transformer 10 is switched to low level, so can be released to the secondary side of transformer 10, secondary side switch current I
sBe formed.Be discharged in the process of secondary side of transformer 10 secondary side switch current I along with energy
sCan descend gradually and finally make zero.Still define: from switching signal V
PWMJust be switched to low level, to secondary side switch current I
sThe time interval that makes zero is t discharge time
DiscAt t discharge time
DiscIn the time interval, switching signal V
PWMBe low level, discharge time signal V
DisBe high levle, anti-discharge time signal V
DisBBe low level.
Then, at switching signal V
PWMStill be low level and secondary side switch current I
sRevert to zero, arrived switching signal V next time
PWMBe switched to the interval during this period of time of high levle again, we are defined as low level time interval t
DisfAt low level time interval t
DisfIn, switching signal V
PWMBe low level, discharge time signal V
DisBe low level, anti-discharge time signal V
DisBBe high levle.
Hereat, we obtain relational expression t
On+ t
Disc+ t
Disf=T.
Wherein, T is switching signal V
PWMCycle.
Output current wave remakes circuit 100 has the input can be in order to receive from difference amplifier 300 outputs and the critical voltage V that feedbacks
ePlease be simultaneously with reference to Fig. 3 and Fig. 5, at high levle time interval t
OnIn, switching signal V
PWMBe high levle, discharge time signal V
DisBe low level, anti-discharge time signal V
DisBBe high levle.Therefore first switch 101 and the 3rd switch 103 are closed, and second switch 102 is opened.At this moment, critical voltage V
eValue be sent to first electric capacity 104 and store, and the first test side V
gMagnitude of voltage corresponding to critical voltage V
e, the second test side V
fGround connection.
At high levle time interval t
OnAfter, switching signal V
PMWBe switched to low level, output current wave remakes circuit 100 and begins to operate in t discharge time
DiscTime interval.At t discharge time
DiscTime interval in, switching signal V
PWMBe low level, discharge time signal V
DisBe high levle, anti-discharge time signal V
DisBBe low level.Therefore first switch 101 and the 3rd switch 103 are opened, and second switch 102 is closed.So, the previous first test side V
gMagnitude of voltage (be critical voltage V
e) can be sent to the second test side V
fBecause second switch 102 is by discharge time signal V
DisControl, therefore at critical voltage V
eBe sent to the second test side V
fProcess in, critical voltage V
eCan be through t discharge time
DiscPhase shift (phaseshift).And at the second test side V
fDetect an amplitude and equal critical voltage V
eAnd time of occurrence and discharge time signal V
DisSynchronous buffering signals V
A 'Buffer 105 is in order to adjust buffering signals V
A 'And output square-wave signal V
a
Buffering signals V
A 'With square-wave signal V
aOscillogram as shown in Figure 7:
Square-wave signal V wherein
aAmplitude be buffering signals V
A 'Amplitude A doubly, square-wave signal V
aTime of occurrence also with discharge time signal V
DisSynchronously.
Wherein, A=(N
P/ N
S)/(2*K), and the value of K is equal to the detection resistance R
SValue.
Hereat, square-wave signal V
aAmplitude be adjusted to V
e* (N
P/ N
S)/(2*K).
Then, at switching signal V next time
PWMBefore being switched to high levle, output current wave remakes circuit 100 and operates in low level time interval t
DisfAt low level time interval t
DisfIn, switching signal V
PWMBe low level, discharge time signal V
DisBe low level, anti-discharge time signal V
DisBBe high levle.Therefore first switch 101 is opened with second switch 102, and the 3rd switch 103 is closed.This moment the first test side V
gNo signal, and the second test side V
fBe grounded.
Hereat, under continuous operation mode, output current wave remakes circuit 100 according to the method, repeatedly to critical voltage V
eThe take a sample value preserving and the signal processing of phase shift (phase shift), and final output current wave remake circuit 100 can be in order to export an amplitude corresponding to critical voltage V
eAnd time of occurrence and discharge time signal V
DisSynchronous square-wave signal V
aBased on this feature, square-wave signal V
aWaveform can be corresponding to output current I
oWaveform.That is to say that output current wave remakes circuit 100 can be in order to reappear one corresponding to output current I
oWaveform.
As shown in Figure 6, low pass filter 200 comprises one first resistance 201 and one second electric capacity 202.Wherein first resistance 201 is connected output current wave and remakes between circuit 100 and the difference amplifier 300.First resistance 201 can be in order to recipient's ripple signal V
a
Second electric capacity 202 is connected to the contact of first resistance 201 and difference amplifier 300.Because second electric capacity 202 has reaction, and second electric capacity 202 and output current wave to remake circuit 100 in parallel.Therefore, second electric capacity 202 can be in order to filtering square-wave signal V
aHFS.
Hereat, low pass filter 200 can be in order to filter square-wave signal V based on the characteristic of its first resistance and second electric capacity
aHFS and export a direct current signal V
b
Direct current signal V
b, square-wave signal V
aWith buffering signals V
A 'Waveform relationship figure can consult Fig. 7 in the lump.
Isolated primary circuit adjuster 20 according to one embodiment of the invention can pass through switching signal V
PWMSwitching transformer 10.Because the output current I of power supply unit
oCan be considered transformer 10 in switching signal V
PWMA period T in, result from an average current of secondary side.So can be expressed as
I
o＝(I
spk*t
disc)/(2*T)------------------------------------(3)
According to formula (1) and formula (2), but our wushu (3) is rewritten as following:
I
o＝(N
P/N
S)*(V
e*t
disc/R
S)/(2*T)-------------------------------(4)
Hereat, by formula (4), we as can be seen, the output current I of power supply unit
oCan obtain stable the adjustment via isolated primary circuit adjuster.
In sum, can and can stablize the output current of adjusting power supply unit by the switching signal switching transformer according to isolated primary circuit adjuster of the present invention.In addition, isolated primary circuit adjuster according to the present invention also adopts the control circuit with back coupling design to replace existing wave mode detector and integrator.Therefore, isolated primary circuit adjuster according to the present invention is not the switched voltage signal of the direct detection primary side that results from transformer, but obtains equivalent critical voltage indirectly.Hereat, not only can stablize the output current of adjusting power supply unit, also can avoid switching the problem of the voltage spring that moment causes because of switch according to the isolated primary circuit adjuster of one embodiment of the invention.
Certainly; the present invention also can have other various embodiments; under the situation that does not deviate from spirit of the present invention and essence thereof; those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of the appended claim of the present invention.
Claims (5)
1. isolated primary circuit adjuster is applied to a primary side of a transformer, it is characterized in that, comprising:
One discharge time detector, connect this transformer, this, detector resulted from a discharge time of switching electric current of a secondary side of this transformer in order to detection discharge time, this, detector was exported a discharge time signal and an anti-discharge time signal discharge time;
One oscillator is in order to produce an oscillator signal;
One control circuit, this control circuit connects this of detector discharge time, and in order to reach this anti-discharge time signal according to this discharge time signal, to a critical voltage carry out that output current wave remakes, filtering, amplification and signal processing relatively, signal is adjusted in this control circuit output one, wherein, this critical voltage switches the peak value of voltage signal corresponding to one of this primary side that results from this transformer, and;
One pulse width modulation device, this pulse width modulation device comprises a first input end and one second input, wherein this first input end connects this control circuit, this second input connects this oscillator, signal is switched in this pulse width modulation device output one, wherein, the work period of this switching signal and frequency are adjusted signal corresponding to this oscillator signal and this, and this adjustment signal is in order to this pulse wave width modulation device of resetting.
2. isolated primary circuit adjuster as claimed in claim 1 is characterized in that, this switched voltage signal is the current signal that magnetizes.
3. isolated primary circuit adjuster as claimed in claim 1 is characterized in that this control circuit comprises:
One output current wave remakes circuit, in order to according to this discharge time signal, this anti-discharge time signal, this switching signal and this critical voltage, export a square-wave signal, wherein, the amplitude of this square-wave signal is corresponding to this critical voltage, the time of occurrence of this square-wave signal and this discharge time signal are synchronous, and the waveform of this square-wave signal is corresponding to the waveform of an output current;
One low pass filter is in order to filter this square-wave signal to export a direct current signal;
One difference amplifier becomes this critical voltage in order to amplify this direct current signal; And
One comparator is connected between this difference amplifier and this pulse width modulation device, this comparator in order to relatively this critical voltage and this switched voltage signal to produce this adjustment signal.
4. isolated primary circuit adjuster as claimed in claim 3 is characterized in that, this output current wave remakes circuit and comprises:
One first switch, the input of this first switch connects this critical voltage, and this first switch is controlled by this switching signal;
One second switch is series at this first switch, and this second switch is controlled by this discharge time signal;
One the 3rd switch connects this second switch, and is parallel to this first switch and this second switch, and the 3rd switch is controlled by this anti-discharge time signal;
One first electric capacity is connected to the contact of this first switch and this second switch, and this first electric capacity is in order to store this critical voltage; And
One buffer is connected to the contact of this second switch and the 3rd switch, and this buffer is in order to buffering and export this square-wave signal.
5. isolated primary circuit adjuster as claimed in claim 3 is characterized in that this low pass filter comprises:
One first resistance is connected this output current wave and remakes between circuit and this difference amplifier, and this first resistance is in order to receive this square-wave signal; And
One second electric capacity is connected to the contact of this first resistance and this difference amplifier, and this second electric capacity is in order to the HFS of this square-wave signal of filtering.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201010145721 CN102215000B (en) | 2010-04-09 | 2010-04-09 | Isolated primary circuit regulator |
Applications Claiming Priority (1)
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| CN 201010145721 CN102215000B (en) | 2010-04-09 | 2010-04-09 | Isolated primary circuit regulator |
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| CN102215000B CN102215000B (en) | 2013-08-21 |
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| CN107026574A (en) * | 2016-01-28 | 2017-08-08 | 英飞凌科技奥地利有限公司 | For the method and apparatus for the load current for estimating Semi-resonance and resonance converter |
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| CN102215000B (en) | 2013-08-21 |
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