CN102468771A - Power converter and undervoltage protection method thereof - Google Patents
Power converter and undervoltage protection method thereof Download PDFInfo
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- CN102468771A CN102468771A CN2010105409384A CN201010540938A CN102468771A CN 102468771 A CN102468771 A CN 102468771A CN 2010105409384 A CN2010105409384 A CN 2010105409384A CN 201010540938 A CN201010540938 A CN 201010540938A CN 102468771 A CN102468771 A CN 102468771A
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Abstract
The invention provides a power converter and an undervoltage protection method thereof. The undervoltage protection method comprises the following steps of: sampling a rectified signal associated with alternating current voltage received by the power converter by using a discrete sampling means; and when the peak of the sampled rectified signal reaches a preset value in a preset period, making a pulse width modulation control chip in the power converter provide a pulse width modulation signal to switch a power switch in the power converter so as to ensure that the power converter provides output voltage to an electronic device, and when the peak of the sampled rectified signal does not reach the preset value in the preset period, making the pulse width modulation control chip stop providing the pulse width modulation signal.
Description
Technical field
The present invention relates to a kind of power supply change-over device and low-voltage protection method thereof, relate in particular to a kind of power supply change-over device that to assist power initiation and under-voltage protection (brown-out protection) function that has.
Background technology
The main purposes of power supply change-over device (power conversion apparatus) is that high pressure and low stable alternating voltage (AC voltage) that Utilities Electric Co. is provided convert suitable various electronic installations (electronic devices) employed low pressure and the preferable direct voltage (DC voltage) of stability to.Therefore, power supply change-over device is widely used in computer, office automation equipment, industrial control equipment, and in the electronic installation such as communication equipment.
Control architecture in the power supply change-over device (control structure) adopts pulse width modulation controlled chip (PWM control chip) mostly now.In fact; The pulse width modulation controlled chip probably can be when the alternating voltage that power supply change-over device received not stablize as yet (for example under-voltage (brown-out), the peak value that can be regarded as the rectified signal that is associated with the alternating voltage that is received does not reach the required minimum voltage of system of electronic installation as yet) just provide pulse-width signal with the power switch (power switch) in switching (be conducting or the close) power supply change-over device.Thus, under the condition of power invariability, the damage that probably can cause the inner member of power supply change-over device and/or electronic installation to recover.
Summary of the invention
In view of this; The present invention proposes a kind of power supply change-over device that can assist power initiation and under-voltage protection function that has; It is able to when the alternating voltage that is received is not stablized as yet (that is under-voltage); Assist to start the power supply of pulse width modulation controlled chip, and cause the pulse width modulation controlled chip to stop to provide pulse-width signal.
The present invention provides a kind of power supply change-over device, and it includes power source conversion level, rectification unit, transformer, first power switch, and the pulse width modulation controlled chip.Wherein, the power source conversion level is in order to receiving an alternating voltage, and said alternating voltage is changed the back and an input voltage is provided.Rectification unit is in order to receiving said alternating voltage, and said alternating voltage carried out after the rectification and a rectified signal is provided.Transformer has primary side, first secondary side and second secondary side; And first end of said primary side is in order to receive said input voltage; Said first secondary side is in order to provide an output voltage to electronic installation, and said second secondary side is then in order to provide a system voltage.
First end of first power switch couples second end of said primary side, and second end of first power switch is coupled to an earthing potential, and the control end of first power switch is then in order to receive a pulse-width signal.The pulse width modulation controlled chip couples rectification unit, transformer and first power switch; In order to receive said system voltage; And operate under the said system voltage through the assistance of said rectified signal; And more use discrete sampling means so that said rectified signal is taken a sample, thereby the peak value of said rectified signal in one preset during in have when reaching a preset value, provide said pulse-width signal to come the power switched switch.
In one embodiment of this invention, the pulse width modulation controlled chip comprises pulse-width signal generator and under-voltage protection unit.Wherein, the pulse-width signal generator couples the control end of first power switch, in order to react on a under-voltage protection signal said pulse-width signal is provided.The under-voltage protection unit couples the pulse-width signal generator; In order to receive and to provide said rectified signal to assist the pulse width modulation controlled chip operation under said system voltage; And use said discrete sampling means so that said rectified signal is taken a sample; Thereby the peak value of said rectified signal in said preset during in have when reaching said preset value, export said under-voltage protection signal.
In one embodiment of this invention, the under-voltage protection unit comprises first resistance, switch, second power switch, first to the 6th transistor, reference current source, comparator, and digital signal processor.Wherein, first end of first resistance is in order to receive said rectified signal.First end of second power switch couples second end of first resistance, and the control end of second power switch is then in order to receive one first control signal.First end of switch couples second end of second power switch, and second end of switch couples said system voltage, and the control end of switch then switches signal in order to receive one.The grid of the first transistor is in order to receive said first control signal, and the drain electrode of the first transistor then couples second end of second power switch.
The grid of transistor seconds and drain electrode couple the source electrode of the first transistor, and the source electrode of transistor seconds then is coupled to said earthing potential.The 3rd transistorized grid couples the grid of transistor seconds, and the 3rd transistorized source electrode then is coupled to said earthing potential.The 4th transistorized source electrode is coupled to a bias voltage, and the 4th transistorized grid then is coupled to the 3rd transistor drain with drain electrode.The 5th transistorized grid couples the 4th transistorized grid, and the 5th transistorized source electrode then is coupled to said bias voltage.Reference current source is coupled between the 5th transistor drain and the said earthing potential.The 6th transistorized grid is in order to one second control signal of reception with the anti-phase each other of said first control signal, and the 6th transistor drain couples the 5th transistor drain, and the 6th transistorized source electrode then is coupled to said earthing potential.
The first input end of comparator couples the 5th transistor drain, and second input of comparator is in order to receive a reference voltage, and the output of comparator is then in order to export a comparison signal.Digital signal processor is in order to the baseline at power supply change-over device; Said first and second control signal and said switching signal are provided; Causing said rectified signal to assist the pulse width modulation controlled chip operation under said system voltage, and during a running of power supply change-over device, react on a clock pulse signal and said first and second control signal is provided; Through said rectified signal is carried out discrete sampling; And record is associated with the comparison signal of discrete sampling according to this, thus the peak value of said rectified signal in said preset during in have when reaching said preset value, export said under-voltage protection signal.
In one embodiment of this invention, comprise N the cycle of said rectified signal during said the presetting, N is a positive integer.With this understanding; Digital signal processor can carry out the M sub-sampling to each cycle in said N cycle of said rectified signal in first and second control signal that baseline provided of power supply change-over device; Thereby make digital signal processor can carry out the N*M sub-sampling to said rectified signal at the baseline of power supply change-over device, wherein M is less than N.
In one embodiment of this invention, digital signal processor is to i sub-sampling time T that said rectified signal carried out
iIt is i-1 sub-sampling time T
I-1Add a Preset Time, i is the odd number positive integer; And digital signal processor is to i+1 sub-sampling time T that said rectified signal carried out
I+1It is i sub-sampling time T
iAdd the above Preset Time and a shift time Δ T.
In one embodiment of this invention, first and second power switch, first to the 3rd transistor, and the 6th transistor is respectively the N transistor npn npn; And the 4th and the 5th transistor is respectively the P transistor npn npn.
In one embodiment of this invention, transistor seconds is of a size of the 3rd transistorized K doubly, and the 4th and the 5th measure-alike, K is a positive integer.
In one embodiment of this invention, the power source conversion level comprises full-bridge rectifier and filter capacitor.Wherein, full-bridge rectifier is in order to receiving said alternating voltage, and said alternating voltage carried out after the full-wave rectification and exports.Filter capacitor couples full-bridge rectifier, carries out filtering in order to the output to full-bridge rectifier, so that said input voltage to be provided.
In one embodiment of this invention, rectification unit comprises first diode and second diode.Wherein, the anode of first and second diode is in order to receive said alternating voltage, and the negative electrode of first and second diode is then in order to provide said rectified signal.
In one embodiment of this invention, the power supply change-over device of being carried more comprises sensing resistor, is coupled between second end and said earthing potential of first power switch.With this understanding; The pulse width modulation controlled chip more comprises the overcurrent protection unit; Be coupled to the node between first power switch and the sensing resistor; In order to receiving and the voltage of more said node is preset the overcurrent protection reference voltage with one, control the pulse-width signal generator and whether produce said pulse-width signal to determine whether to start an over current protection protection mechanism.
In one embodiment of this invention, the power supply change-over device of being carried more comprises feedback unit, and in order to receiving said output voltage, and output according to this is associated with a feedback signal of the load condition of electronic installation.With this understanding, the pulse width modulation controlled chip is more in order to adjust said pulse-width signal according to said feedback signal.
The present invention provides a kind of low-voltage protection method that is suitable for power supply change-over device, and it comprises: utilization discrete sampling means are to take a sample to the rectified signal that is associated with the alternating voltage that power supply change-over device received; And when by the peak value of the rectified signal of being taken a sample in one preset during in have when reaching a preset value; Then the pulse width modulation controlled chip in the render electrical supply changeover device provides pulse-width signal with the power switch in the Switching power conversion equipment, thereby makes power supply change-over device provide output voltage to electronic installation; Otherwise, cause the pulse width modulation controlled chip to stop to provide pulse-width signal.
Based on above-mentioned, power supply change-over device proposed by the invention and low-voltage protection method thereof mainly are that utilization discrete sampling means (being the mode of Digital Signal Processing) are to take a sample to the rectified signal that is associated with the alternating voltage that power supply change-over device received.In case by the peak value of the rectified signal of being taken a sample in one preset during in have when reaching a preset value that (alternating voltage that power supply change-over device received is stable; Or the required minimum voltage of the system that has reached electronic installation), then cause the pulse width modulation controlled chip to provide pulse-width signal with the power switched switch; Otherwise (be that the alternating voltage that power supply change-over device receives is stablized as yet, or also do not reach the required minimum voltage of system of electronic installation) causes the pulse width modulation controlled chip to stop to provide pulse-width signal.Thus, can solve the problem that prior art is addressed effectively.
For letting the above-mentioned feature and advantage of the present invention can be more obviously understandable, hereinafter is special lifts embodiment, and cooperates appended graphic elaborating as follows.
Description of drawings
Fig. 1 is the sketch map of the power supply change-over device of one embodiment of the invention.
Fig. 2 is the sketch map of the power source conversion level of one embodiment of the invention.
Fig. 3 is the sketch map of the rectification unit of one embodiment of the invention.
Fig. 4 is the sketch map of the under-voltage protection unit of one embodiment of the invention.
Fig. 5 is the running key-drawing of the under-voltage protection unit of one embodiment of the invention.
Fig. 6 is the alternating voltage of one embodiment of the invention and the sketch map of system voltage.
The sketch map of the rectified signal that Fig. 7 is taken a sample for the superposition of one embodiment of the invention.
Fig. 8 is the low-voltage protection method flow chart that is suitable for power supply change-over device of one embodiment of the invention.
Main description of reference numerals:
10: power supply change-over device; 101: the power source conversion level;
103: rectification unit; 105: the pulse width modulation controlled chip;
107: feedback unit; 109: the pulse-width signal generator;
111: the under-voltage protection unit; 113: the overcurrent protection unit;
201: full-bridge rectifier; 401: comparator;
403: digital signal processor (DSP); T: transformer;
P: primary side; S
1, S
2: secondary side;
Q
1, Q
2: power switch; R
S, R: sensing resistor;
D
1, D
2, DF
1, DF
2: diode; C
1, C
2: electric capacity; Cap: filter capacitor;
LD: electronic installation; M
1～M
6: transistor;
SW: switch; I: reference current source;
Vref: reference voltage; Vbias: bias voltage;
Ip: the electric current of the primary side of the transformer of flowing through; V
CC: system voltage;
V
OUT: output voltage; V
IN: input voltage;
AC_IN: alternating voltage; AC_IN ': rectified signal;
V
FB: feedback signal V
PWM: pulse-width signal
V
CS: the voltage of node; N: node;
V
OCP: preset overcurrent protection reference voltage; BOP: under-voltage protection signal;
CS
1, CS
2: control signal; CMP: comparison signal;
CLK: clock signal; SS: switching signal;
T
0～T
47: the time V of sampling
UVLO:
The minimum operation of pulse width modulation controlled chip
Press;
INI: the baseline of power supply change-over device; OPE: during the running of power supply change-over device;
S801～S807：
Each step of low-voltage protection method flow chart that is suitable for power supply change-over device of one embodiment of the invention.
Embodiment
Existing with detailed reference example embodiment of the present invention, the instance of said example embodiment will be described in the accompanying drawings.In addition, all possibility parts use element/member of same numeral to represent identical or similar portions in graphic and execution mode.
Fig. 1 is the sketch map of the power supply change-over device (power conversion apparatus) of one embodiment of the invention.Please with reference to Fig. 1, power supply change-over device 10 comprises power source conversion level (power conversion stage) 101, rectification unit (rectification unit) 103, pulse width modulation controlled chip (PWM control chip) 105, feedback unit (feedback unit) 107, transformer (transformer) T, power switch (power switch) Q
1, sensing resistor (sensing resistor) R
S, diode (diode) D
1With D
2, and electric capacity (capacitor) C
1With C
2
In the present embodiment, power source conversion level 101 is in order to receiving alternating voltage (AC voltage) AC_IN, and alternating voltage AC_IN is changed the back and input voltage (input voltage) V is provided
INClearer, Fig. 2 is the sketch map of the power source conversion level of one embodiment of the invention.Please with reference to Fig. 2; Power source conversion level 101 can be a kind of full-bridge type power supply changeover device (full bridge power converter), and can include full-bridge rectifier (full-bridge rectifier) 201 and filter capacitor (filter capacitor) Cap.Wherein, full-bridge rectifier 201 is in order to receiving alternating voltage AC_IN, and alternating voltage AC_IN is carried out exporting after the full-wave rectification.Filter capacitor Cap couples full-bridge rectifier 201, carries out filtering in order to the output to full-bridge rectifier 201, so that input voltage V to be provided
IN
In simple terms, in case after power source conversion level 101 received the alternating voltage AC_IN that for example Utilities Electric Co. provided, power source conversion level 101 will be carried out full-wave rectification and filtering to the alternating voltage AC_IN that is received, thereby input voltage V is provided
INYet the present invention is not restricted to this.That is, the power supply changeover device of other types is also applicable to the present invention, for example semibridge system power supply changeover device (half bridge power converter).
Transformer T has primary side (primary side) P and secondary side (secondary side) S
1With S
2Wherein, first end of the primary side P of transformer T is in order to receive input voltage V
INThe secondary side S of transformer T
1In order to react on power switch Q
1Switching and output voltage V is provided
OUTGive electronic installation (electronic device) LD; And the secondary side S of transformer T
2In order to react on power switch Q
1Switching and system voltage (system voltage) V is provided
CC
In general, be reflected at the secondary side S of transformer T
1Alternating voltage (by first and second side P and the S of transformer T
1Coil determine than (turn ratio)) can be via diode D
1Rectification and capacitor C
1Filtering after to convert output voltage V to
OUTSimilarly, be reflected at the secondary side S of transformer T
2Alternating voltage (by first and second side P and the S of transformer T
2Coil than determine) also can be via diode D
2Rectification and capacitor C
2Filtering after to convert system voltage V to
CC
Power switch Q
1First end couple second end of the primary side P of transformer T; Power switch Q
1Second end can see through sensing resistor Rs and be coupled to an earthing potential (ground potential); And power switch Q
1Control end in order to receive pulse-width signal (PWM signal) V that pulse width modulation controlled chip 105 is provided
PWM Feedback unit 107 is in order to receive output voltage V
OUT, and output according to this is associated with the feedback signal V of the load condition (loading status) of electronic installation LD
FBThereby, make that pulse width modulation controlled chip 105 can be according to feedback signal V
FBAdjust the pulse-width signal V that it provides
PWM
What deserves to be mentioned is at this; As long as can export that any circuit kenel (for example utilize resitstance voltage divider arrange in pairs or groups the feedback circuit of optical coupler) of the feedback signal of the load condition that is associated with electronic installation LD can be used as is the feedback unit 107 of present embodiment, so present embodiment is at this execution mode of limit feedback circuit 107 not.
Pulse width modulation controlled chip 105 couples rectification unit 103, transformer T and power switch Q
1, in order to receiving system voltage V
CC, and operate in system voltage V through the assistance of rectified signal AC_IN '
CCDown; And more use discrete sampling means (discretes ampling means) so that rectified signal AC_IN ' is taken a sample; Thereby in the peak value (peak value) of rectified signal AC_IN ' (details) during one presets at the back, have when reaching a preset value (the for example required minimum voltage of the system of electronic installation LD) again, pulse-width signal V is provided
PWMCome power switched switch Q
1
Clearer; Pulse width modulation controlled chip 105 can include pulse-width signal generator (PWM signal generator) 109, under-voltage protection unit (brown-out protection unit) 111, and overcurrent protection unit (over-current protection unit) 113.Wherein, pulse-width signal generator 109 couples power switch Q
1Control end, in order to react on under-voltage protection signal (brown-out signal) BOP that exports under-voltage protection unit 111 pulse-width signal V is provided
PWM
Under-voltage protection unit 111 couples pulse-width signal generator 109, in order to receive and to provide rectified signal AC_IN ' to operate in system voltage V to assist pulse width modulation controlled chip 105
CCDown; And utilization discrete sampling means are to take a sample to rectified signal AC_IN '; Thereby the required minimum voltage of the system that reaches electronic installation LD (90Vac is for example arranged in N the cycle of rectified signal AC_IN ' (N is a positive integer) at the peak value of rectified signal AC_IN '; But be not restricted to this) time, output under-voltage protection signal BOP provide pulse-width signal V to cause pulse-width signal generator 109
PWM
In this; Please look back the described content of this case prior art earlier; Traditionally; The pulse width modulation controlled chip probably can be when the alternating voltage that power supply change-over device received not stablize as yet (for example under-voltage, the peak value that can be regarded as the rectified signal that is associated with the alternating voltage that is received does not reach the required minimum voltage of system of electronic installation as yet) just provide pulse-width signal with the power switch in switching (be conducting or the close) power supply change-over device.Thus, under the condition of power invariability, the damage that probably can cause the inner member of power supply change-over device and/or electronic installation to recover.
In view of this; Present embodiment utilizes under-voltage protection unit 111 to solve the problem that this case prior art is addressed especially; And it is (under-voltage when its alternating voltage AC_IN that is able to be received at power supply change-over device 10 does not stablize as yet; Or the required minimum voltage of the system that does not also reach electronic installation LD), assist to start the power supply of pulse width modulation controlled chip 105, and cause pulse width modulation controlled chip 105 to stop to provide pulse-width signal V
PWMThereby, avoid the inner member of power supply change-over device and/or electronic installation to cause the damage that can't recover.
Clearer, Fig. 4 is the sketch map of the under-voltage protection unit of one embodiment of the invention.Please with reference to Fig. 4, under-voltage protection unit 111 can include resistance R, power switch Q
2, switch (switch) SW, transistor (transistor) M
1～M
6, reference current source (reference current source) I, comparator (comparator) 401, and digital signal processor (digital signal processor, DSP) 403.In the present embodiment, first end of resistance R is in order to receive rectified signal AC_IN '.Power switch Q
2First end couple second end of resistance R, and power switch Q
2Control signal (control signal) CS that then provided of control end in order to receiving digital signals processor (DSP)
1First end of switch SW couples power switch Q
2Second end; Second end of switch SW is coupled to system voltage V
CCSwitching signal (switching signal) SS that the control end of switch SW is then provided in order to receiving digital signals processor (DSP).
Transistor M
1Grid (gate) in order to receive control signal CS
1, and transistor M
1Drain electrode (drain) then couple power switch Q
2Second end.Transistor M
2Grid and drain electrode couple transistor M
1Source electrode (source), and transistor M
2Source electrode then be coupled to earthing potential.Transistor M
3Grid couple transistor M
2Grid, and transistor M
3Source electrode then be coupled to earthing potential.Wherein, transistor M
2Be of a size of transistor M
3K doubly (K is a positive integer), for example be 100, but be not restricted to this.
Transistor M
4Source electrode be coupled to bias voltage (bias voltage) Vbias, and transistor M
4Grid then be coupled to transistor M with drain electrode
3Drain electrode.Transistor M
5Grid couple transistor M
4Grid, and transistor M
5Source electrode then be coupled to bias voltage Vbias.Wherein, transistor M
4With M
5Measure-alike.Reference current source I is coupled to transistor M
5Drain electrode and earthing potential between.Transistor M
6Grid with receiving and control signal CS
1The control signal CS of anti-phase each other
2Transistor M
6Drain electrode couple transistor M
5Drain electrode; And transistor M
6Source electrode then be coupled to earthing potential.In this, above-mentioned power switch Q
1With Q
2And transistor M
1～M
3With M
6Can be respectively N transistor npn npn (N-type transistor); In addition, transistor M
4With M
5Can be respectively P transistor npn npn (P-type transistor).
The first input end of comparator 401 (promptly just (positive ,+) input) couples transistor M
5Drain electrode; Second input of comparator 401 (promptly negative (negative,-) input) in order to receive reference voltage Vref; The output of comparator 401 is then in order to output comparison signal CMP.Wherein, the electric current of reference current source I (Iref) can equal reference voltage Vref divided by a preset resistance (Rpre), that is: Iref=Vref/Rpre.
Can seem; When digital signal processor 403 never reaches the required minimum voltage of the system of electronic installation LD at the peak value of rectified signal AC_IN ' in N the cycle of rectified signal AC_IN ' (alternating voltage AC_IN is stable as yet); Then do not export under-voltage protection signal BOP and give pulse-width signal generator 109, thus make pulse-width signal generator 109 stop to provide/produce pulse-width signal V
PWMGive power switch Q
1
Thus; (for example under-voltage (brown-out), the peak value that can be regarded as the rectified signal AC_IN ' that is associated with the alternating voltage AC_IN that is received does not reach the required minimum voltage of system of electronic installation LD as yet) do not stop to provide pulse-width signal V when the alternating voltage AC_IN that can make pulse width modulation controlled chip 105 received at power supply change-over device 10 stablized as yet
PWMThereby, stop the power switch Q in the power supply change-over device 10
1Switching (be conducting or close), cause the damage that can't recover with the inner member of avoiding power supply change-over device 10 and/or electronic installation LD.
Clearer, Fig. 5 is the running key-drawing of the under-voltage protection unit of one embodiment of the invention.Please merge with reference to Fig. 4 and Fig. 5; At first; Baseline INI at power supply change-over device 10; For example power supply change-over device 10 rigidly connects the alternating voltage AC_IN that receives that Utilities Electric Co. provides because alternating voltage AC_IN is stable as yet, so digital signal processor 403 during this period (INI) the control signal CS of high levle can be provided constantly
1Control signal CS with switching signal SS and low level
2With under-voltage protection signal BOP.Also because of like this, pulse-width signal generator 109 just reacts on the under-voltage protection signal BOP of low level and stops to provide pulse-width signal V
PWMGive power switch Q
1
Meanwhile, power switch Q
2Distinctly react on the control signal CS of high levle with switch SW
1The conducting with switching signal SS, thus make that rectified signal AC_IN ' can be via resistance R, power switch Q
2Be provided to the secondary side S that is reflected at transformer T with the conduction of switch SW
2On system voltage V
CCThus, rectified signal AC_IN ' will assist pulse width modulation controlled chip 105 to be able to operate in system voltage V
CCFollowing, that is: the minimum operation voltage V that reaches pulse width modulation controlled chip 105
UVLO(Fig. 6 is the alternating voltage of one embodiment of the invention and the sketch map of system voltage, from system voltage V shown in Figure 6
CCRamp-up period can find out).Assist pulse width modulation controlled chip 105 to be able to operate in system voltage V at rectified signal AC_IN '
CCUnder the time, digital signal processor 403 will change control signal CS
1With CS
2And the state of switching signal SS, and keep the state of under-voltage protection signal BOP, thus close power switch Q
2With switch SW.In other words, at the baseline INI of power supply change-over device 10, under-voltage protection unit 111 can conducting power switch Q
2With the power supply of switch SW with assistance startup pulse width modulation controlled chip 105.In case after starting the power supply of pulse width modulation controlled chip 105, then close power switch Q
2With switch SW.
On the other hand; OPE during the running of power supply change-over device 10; Because alternating voltage AC_IN also might be unstable as yet; Be that the peak value of rectified signal AC_IN ' does not reach the required minimum voltage of the system of electronic installation LD (for example 90Vac, but be not restricted to this) as yet, thus digital signal processor 403 during this period (OPE) just intermittently (discretely) control signal CS is provided
1With CS
2, so that rectified signal AC_IN ' is carried out discrete sampling.In one embodiment of this invention, the digital signal processor 403 control signal CS that OPE provided during the running of power supply change-over device 10
1With CS
2Can carry out two sub-samplings (can clearly be seen that from Fig. 5, but be not restricted to this) to each cycle in N cycle (cycle) of rectified signal AC_IN ' (N=24, but be not restricted to this, promptly aforesaid preset during), that is: take a sample altogether 48 times.
In addition, the sketch map of Fig. 7 rectified signal of being taken a sample for the superposition of one embodiment of the invention.As if these 24 cycles are carried out crossover, then can be as shown in Figure 7, and the time T of this sampling of 48 times
0～T
47Can represent respectively as follows:
T
0=0 (be start time point, but be not restricted to this);
T
1=T
0+ 4ms (being Preset Time);
T
2=T
1+ 4ms+ Δ T (Δ T=0.15ms, i.e. shift time, but be not restricted to this);
T
3＝T
2+4ms；
T
4＝T
3+4ms+ΔT；
T
5＝T
4+4ms；
T
6＝T
5+4ms+ΔT；
…；
T
46=T
45+ 4ms+ Δ T; And
T
47＝T
46+4ms。
Under this condition of base, the frequency (frequency) of the clock signal CLK that digital signal processor 403 is received can be set at 65KHz, but based on different imposing a condition, the frequency of clock signal CLK also can change thereupon, and all are looked the actual design demand and discuss.
In view of this, OPE during the running of power supply change-over device 10 is as control signal CS
1During for high levle, represent that then desire takes a sample to rectified signal AC_IN '.And to sampling each time, comparator 401 all can be exported corresponding comparison signal CMP and give digital signal processor 403.For instance, as the transistor M that is reflected at that rectified signal AC_IN ' is taken a sample
5Electric current during less than the electric current (Iref) of reference current source I, then comparator 401 all can be exported the for example comparison signal CMP of low level; Otherwise, as the transistor M that is reflected at that rectified signal AC_IN ' is taken a sample
5Electric current during greater than the electric current (Iref) of reference current source I, then comparator 401 all can be exported the for example comparison signal CMP of high levle.Thus, digital signal processor 403 promptly can obtain 48 comparison signal CMP that correspond respectively to 48 sub-samplings that rectified signal AC_IN ' is carried out, and carries out record thus again.
In case one of them of 48 comparison signal CMP that obtained is the words of high levle; Then digital signal processor 403 will be judged alternating voltage AC_IN stable (being the required minimum voltage (90Vac) of system that the peak value of rectified signal AC_IN ' has reached electronic installation LD), thereby the under-voltage protection signal BOP that high levle is provided after rectified signal AC_IN ' is finished 48 sub-samplings is to pulse-width signal generator 109.Thus, pulse-width signal generator 109 will begin to provide pulse-width signal V
PWMWith power switched switch Q
1Thereby, make power supply change-over device 10 supply output voltage V
OUTGive electronic installation LD.In other words, OPE during the running of power supply change-over device 10, under-voltage protection unit 111 can cause pulse width modulation controlled chip 105 to stop to provide pulse-width signal V when alternating voltage AC_IN does not stablize as yet
PWM, till alternating voltage AC_IN is stable (being the required minimum voltage (90Vac) of system that the peak value of rectified signal AC_IN ' has reached electronic installation LD).Thus, can solve the problem that prior art is addressed effectively.
Based on the content that the foregoing description disclosed, below will converge and put in order out a kind of low-voltage protection method that is suitable for power supply change-over device and consider and examine/reference for the those of ordinary skill in field of the present invention.
Fig. 8 is the low-voltage protection method flow chart that is suitable for power supply change-over device of one embodiment of the invention.Please with reference to Fig. 8, the low-voltage protection method of present embodiment comprises:
Utilization discrete sampling means are with the rectified signal that is associated with the alternating voltage that power supply change-over device received is taken a sample (step S801);
The peak value of the rectified signal that judgement is taken a sample has or not in during preset and reaches preset value (step S803); And
When in the peak value of the rectified signal of being taken a sample is during preset the preset value of reaching being arranged; Then the pulse width modulation controlled chip in the render electrical supply changeover device provides pulse-width signal with the power switch in the Switching power conversion equipment, thereby makes power supply change-over device provide output voltage to electronic installation (step S805); Otherwise, cause the pulse width modulation controlled chip to stop to provide pulse-width signal (step S807).
In sum; Power supply change-over device proposed by the invention can be when the alternating voltage that it received not be stablized as yet (under-voltage); Assist to start the power supply of pulse width modulation controlled chip earlier, thereby let the pulse width modulation controlled chip can implement under-voltage protection mechanism further.And power supply change-over device proposed by the invention and low-voltage protection method thereof mainly are that utilization discrete sampling means (being the mode of Digital Signal Processing) are to take a sample to the rectified signal that is associated with the alternating voltage that power supply change-over device received.In case by the peak value of the rectified signal of being taken a sample in one preset during in have when reaching a preset value that (alternating voltage that power supply change-over device received is stable; Or the required minimum voltage of the system that has reached electronic installation), then cause the pulse width modulation controlled chip to provide pulse-width signal with the power switched switch; Otherwise (be that the alternating voltage that power supply change-over device receives is stablized as yet, or also do not reach the required minimum voltage of system of electronic installation) causes the pulse width modulation controlled chip to stop to provide pulse-width signal.Thus, can avoid the inner member of power supply change-over device and/or electronic installation to cause the damage that can't recover.
Though the present invention with the embodiment explanation as above; Right its is not in order to limit the present invention; The those of ordinary skill of technical field under any; Do not breaking away from the spirit and scope of the present invention, changing or be equal to replacement, so protection scope of the present invention is as the criterion with the application's the scope that claim was defined when making part.
Claims (15)
1. a power supply change-over device is characterized in that, comprising:
One power source conversion level in order to receiving an alternating voltage, and is changed the back and an input voltage is provided this alternating voltage;
One rectification unit in order to receiving this alternating voltage, and carries out after the rectification this alternating voltage and a rectified signal is provided;
One transformer; Have a primary side, one first secondary side and one second secondary side; Wherein first end of this primary side is in order to receive this input voltage, and this first secondary side is in order to provide an output voltage to an electronic installation, and this second secondary side is then in order to provide a system voltage;
One first power switch, its first end couples second end of this primary side, and its second end is coupled to an earthing potential, and its control end is then in order to receive a pulse-width signal; And
One pulse width modulation controlled chip; Couple this rectification unit, this transformer and this first power switch; In order to receiving this system voltage, and operate under this system voltage, and more use discrete sampling means so that this rectified signal is taken a sample through the assistance of this rectified signal; Thereby the peak value of this rectified signal in one preset during in have when reaching a preset value, provide this pulse-width signal to switch this first power switch.
2. power supply change-over device according to claim 1 is characterized in that, wherein this pulse width modulation controlled chip comprises:
One pulse-width signal generator couples the control end of this first power switch, in order to react on a under-voltage protection signal this pulse-width signal is provided; And
One under-voltage protection unit; Couple this pulse-width signal generator; In order to receive and to provide this rectified signal to assist this pulse width modulation controlled chip operation under this system voltage; And use these discrete sampling means so that this rectified signal is taken a sample, thereby in the peak value of this rectified signal is during this is preset, have when reaching this preset value, export this under-voltage protection signal.
3. power supply change-over device according to claim 2 is characterized in that, wherein this under-voltage protection unit comprises:
One first resistance, its first end is in order to receive this rectified signal;
One second power switch, its first end couples second end of this first resistance, and its control end is then in order to receive one first control signal;
One switch, its first end couples second end of this second power switch, and its second end couples this system voltage, and its control end then switches signal in order to receive one;
One the first transistor, its grid is in order to receive this first control signal, and its drain electrode then couples second end of this second power switch;
One transistor seconds, its grid and its drain electrode couple the source electrode of this first transistor, and its source electrode then is coupled to this earthing potential;
One the 3rd transistor, its grid couples the grid of this transistor seconds, and its source electrode then is coupled to this earthing potential;
One the 4th transistor, its source electrode is coupled to a bias voltage, and its grid and its drain electrode then are coupled to the 3rd transistor drain;
One the 5th transistor, its grid couple the 4th transistorized grid, and its source electrode then is coupled to this bias voltage;
One reference current source is coupled between the 5th transistor drain and this earthing potential;
One the 6th transistor, its grid is in order to one second control signal of reception with this first control signal anti-phase each other, and its drain electrode couples the 5th transistor drain, and its source electrode then is coupled to this earthing potential;
One comparator, its first input end couples the 5th transistor drain, and its second input is in order to receive a reference voltage, and its output is then in order to export a comparison signal; And
One digital signal processor; In order to a baseline at this power supply change-over device, provide this first with this second control signal and this switching signal, assist this pulse width modulation controlled chip operation under this system voltage to cause this rectified signal; And during a running of this power supply change-over device; React on a clock pulse signal and provide this first with this second control signal, through this rectified signal being carried out a discrete sampling, and record is associated with this comparison signal of this discrete sampling according to this; Thereby in the peak value of this rectified signal is during this is preset, have when reaching this preset value, export this under-voltage protection signal.
4. power supply change-over device according to claim 3 is characterized in that, comprises N the cycle of this rectified signal during wherein should presetting, and N is a positive integer.
5. power supply change-over device according to claim 4; It is characterized in that; Wherein this digital signal processor this power supply change-over device this baseline provided that this first can carry out the M sub-sampling to each cycle in said N cycle of this rectified signal with this second control signal; Thereby make this digital signal processor carry out the N*M sub-sampling at this baseline of this power supply change-over device to this rectified signal, wherein M is less than N.
6. power supply change-over device according to claim 5 is characterized in that, wherein
This digital signal processor is to i sub-sampling time T that this rectified signal carried out
iIt is i-1 sub-sampling time T
I-1Add a Preset Time, i is the odd number positive integer; And
This digital signal processor is to i+1 sub-sampling time T that this rectified signal carried out
I+1It is i sub-sampling time T
iAdd this Preset Time and a shift time Δ T.
7. power supply change-over device according to claim 3 is characterized in that, wherein
This first with this second power switch, this first to the 3rd transistor, and the 6th transistor is respectively a N transistor npn npn; And
The 4th with the 5th transistor be respectively a P transistor npn npn.
8. power supply change-over device according to claim 3 is characterized in that, wherein this transistor seconds is of a size of the 3rd transistorized K doubly, and the 4th with the 5th transistorized measure-alike, and K is a positive integer.
9. power supply change-over device according to claim 1 is characterized in that, wherein this power source conversion level comprises:
One full-bridge rectifier in order to receiving this alternating voltage, and carries out exporting after the full-wave rectification to this alternating voltage; And
One filter capacitor couples this full-bridge rectifier, carries out filtering in order to the output to this full-bridge rectifier, so that this input voltage to be provided.
10. power supply change-over device according to claim 1 is characterized in that, wherein this rectification unit comprises:
One first diode; And
One second diode,
Wherein, this first with the anode of this second diode in order to receiving this alternating voltage, this first with the negative electrode of this second diode then in order to this rectified signal to be provided.
11. power supply change-over device according to claim 1 is characterized in that, more comprises:
One sensing resistor is coupled between second end and this earthing potential of this first power switch.
12. power supply change-over device according to claim 11 is characterized in that, wherein this pulse width modulation controlled chip more comprises:
One overcurrent protection unit; Be coupled to the node between this first power switch and this sensing resistor; In order to receiving and the relatively voltage and a preset overcurrent protection reference voltage of this node, control this pulse-width signal generator and whether produce this pulse-width signal to determine whether to start an over current protection protection mechanism.
13. power supply change-over device according to claim 1 is characterized in that, more comprises:
One feedback unit, in order to receiving this output voltage, and output according to this is associated with a feedback signal of the load condition of this electronic installation.
14. power supply change-over device according to claim 13 is characterized in that, wherein this pulse width modulation controlled chip is more in order to adjust this pulse-width signal according to this feedback signal.
15. a low-voltage protection method is suitable for a power supply change-over device, it is characterized in that, and this low-voltage protection method comprises:
Use discrete sampling means to take a sample to being associated with the rectified signal that this power supply change-over device one of received alternating voltage; And
When the peak value of this rectified signal of being taken a sample in one preset during in have when reaching a preset value; Then cause a pulse width modulation controlled chip in this power supply change-over device to provide a pulse-width signal switching the power switch in this power supply change-over device, thereby make this power supply change-over device provide an output voltage to an electronic installation; Otherwise, cause this pulse width modulation controlled chip to stop to provide this pulse-width signal.
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| CN2010105409384A CN102468771A (en) | 2010-11-09 | 2010-11-09 | Power converter and undervoltage protection method thereof |
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| CN2010105409384A CN102468771A (en) | 2010-11-09 | 2010-11-09 | Power converter and undervoltage protection method thereof |
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| CN107396483A (en) * | 2016-05-17 | 2017-11-24 | 力林科技股份有限公司 | Power supply conversion device |
| CN107872244A (en) * | 2016-09-22 | 2018-04-03 | 成都长城开发科技有限公司 | The method and device of power line carrier communication test |
| CN110854819A (en) * | 2019-12-13 | 2020-02-28 | 陕西亚成微电子股份有限公司 | Method and circuit for integrating discharge and input under-voltage protection of Xcap capacitor |
| CN112444665A (en) * | 2019-08-28 | 2021-03-05 | 光宝电子(广州)有限公司 | Electronic device, voltage detector and voltage detection method thereof |
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| CN110854819A (en) * | 2019-12-13 | 2020-02-28 | 陕西亚成微电子股份有限公司 | Method and circuit for integrating discharge and input under-voltage protection of Xcap capacitor |
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Application publication date: 20120523 |