CN100525025C - Starting circuit with feedforward compensation for power converter - Google Patents
Starting circuit with feedforward compensation for power converter Download PDFInfo
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- CN100525025C CN100525025C CNB2006101271862A CN200610127186A CN100525025C CN 100525025 C CN100525025 C CN 100525025C CN B2006101271862 A CNB2006101271862 A CN B2006101271862A CN 200610127186 A CN200610127186 A CN 200610127186A CN 100525025 C CN100525025 C CN 100525025C
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Abstract
This invention relates to a starting up circuit of a power converter, since the power converter contains a bleeding resistor, the electromagnetism of which is used to interfere with filters. In order to save power and reduce numbers of elements, this invention uses the bleeding resistor in start-up and front feed compensation including an input end used in coupling to the bleeding resistor, a bleeding circuit coupled to the input end, a sample preservation circuit sampling from the bleeding circuit and preserving a voltage signal, a low pass filter coupling to the sample preservation circuit to generate an offset signal based on the voltage signal to be transmitted to a limit circuit to generate a limit signal used in limiting switch current of the power converter.
Description
Technical field
The invention relates to a kind of power converter, be meant a kind of control circuit of switching power converter especially.
Background technology
Press, switching power converter is a kind of conventional art, is used to control power output to reach the purpose of adjustment.Generally speaking, have the kinds of protect function in the power converter, for example overvoltage protection and overcurrent protection etc. avoid being subjected to permanent lesion with the circuit of protecting power converter and being connected.The power output limitation function generally is usually used in overload protection and short-circuit protection.
See also Fig. 1, it is the circuit diagram of a traditional switching power converter.As shown in the figure, traditional switching power converter is to use a control circuit 50.Work as electric power starting, an input voltage V
DCStarting resistance 30 chargings one via a series connection start electric capacity 65, so that a supply voltage V to be provided
CCStart the feed end VCC that electric capacity 65 is coupled to control circuit 50.Supply voltage V
CCWhen reaching critical voltage, power converter can come into operation and the output OUT of control circuit 50 begins output output one switching signal V
PWMAnd the driving power transducer.After power converter started, the auxiliary winding of a transformer 20 saw through a rectifier 60 supply voltage V is provided
CC
One power electric crystal 10, it is coupled to the first side winding of transformer 20 and the output OUT of control circuit 50, and power electric crystal 10 is according to switching signal V
PWMSwitching transformer 20 is with the power output of power controlling transducer.One resistance 15, it is series at power electric crystal 10, and the peak power output of decision power converter.The method is to couple the current sense end VS of a resistance 40 in control circuit 50.If voltage V
SSurpass a maximum critical value, control circuit 50 will switch signal V by forbidden energy
PWM, with the peak power output of power-limiting transducer.Yet peak power output can be subjected to a response time T
DInfluence, this time is meant the voltage V of position at current sense end VS
SWhen being higher than maximum critical value by detecting, the switching signal V of control circuit 50
PWMCan be again through one time of delay T
DAfter just end.Time of delay T
DBe according to input voltage V
DCVariation and cause different overpower protections.
One resistance 35, it is coupled to input voltage V
DCAnd between the current sense end VS, to be used for feedforward compensation.Feedforward compensation is in order to compensation input voltage V
DCWith T time of delay
DThe power output that is caused is inconsistent.By the appropriate resistance value of selecting resistance 35, the power output restriction that can when low line voltage (low line voltage) is imported with high line voltage (high line voltage), agree.Because resistance 30 can cause tangible power loss with resistance 35, particularly when high line voltage is imported.So propose now to use a resistance to carry out feedforward compensation and startup, it is exposed in the United States Patent (USP)s that the people proposed the 6th such as Mr. Yang, 611, No. 439 " PWM controller for controllingoutput power limit of a power supply ".In addition, " the Integrated start-upcircuit with reduced power consumption " that No. the 6th, 906,934, the United States Patent (USP)s that the people proposed such as Mr. Yang, more cpable of lowering power loss.Yet, United States Patent (USP) the 6th, 906, No. 934 disclosed technology can't be applied to United States Patent (USP) the 6th, 611,439 disclosed circuit.
Therefore, the present invention proposes a kind of start-up circuit of power converter, and to solve above-mentioned located by prior art problem, the present invention is to use a resistance to reach the purpose of startup, feedforward compensation and safety in order to save power and to reduce component number.
Summary of the invention
Main purpose of the present invention is to provide a kind of start-up circuit of power converter, and it is by using a resistance to reach startup, feedforward compensation and safety, to reach power loss of saving power converter and the purpose that reduces number of elements.
The present invention is in order to save power and to reduce number of elements, and the present invention uses a bleeder resistance to start and feedforward compensation.Based on safety, power converter must be provided with bleeder resistance, with the Electromagnetic interference filter of the power converter of releasing.Circuit of the present invention comprises an input and couples bleeder resistance to be used for startup; One bleeder circuit, it is coupled to input; Circuit is preserved in one sampling, and it couples bleeder circuit, to take a sample from bleeder circuit and to preserve a voltage signal; Afterwards, a low pass filter, it is used to filter line frequency ripple and produces a skew signal according to voltage signal, and low pass filter is a sampling filter.The skew signal is to be sent to a restricting circuits, and to produce a restriction signal, the restriction signal switches electric current in order to one of power-limiting transducer.
The invention has the beneficial effects as follows: use a resistance to reach startup, feedforward compensation and safety, can save the power loss of power converter and reduce number of elements.
Description of drawings
Fig. 1 is the circuit diagram of a traditional switching power converter;
Fig. 2 is the circuit diagram of switching power converter of the present invention;
Fig. 3 is the circuit diagram of the start-up circuit of tool feedforward compensation of the present invention;
Fig. 4 produces the circuit diagram of the generation circuit of sampled signal for the present invention;
Fig. 5 is the oscillogram of sampled signal of the present invention.
The figure number explanation:
10 power electric crystals, 15 resistance
17 power electric crystals, 19 resistance
20 transformers, 25 transformers
30 starting resistances, 35 resistance
40 resistance, 50 control circuits
51 Zener diodes, 53 resistance
55 optical couplers, 57 rectifiers
59 filter capacitors, 60 rectifiers
65 start electric capacity 67 diodes
69 start electric capacity 70 bleeder resistances
90 bridge circuits, 100 control circuits
110 first comparators, 120 second comparators
150 oscillators, 160 NAND gate
180 rest-set flip-flops, 200 start-up circuits
205 diodes, 207 bleeder circuits
210 resistance, 220 resistance
Circuit is preserved in 230 samplings of 225 switches
231 first sampling switches, 235 first electric capacity
240 low pass filters, 241 second sampling switches
245 second electric capacity, 250 restricting circuits
255 adders, 260 reference voltages
300 counter 310 and locks
350 first one shots, 360 second one shots
FB feedbacks end GND earth terminal
I
PSwitch current N
SSecondary side winding
OUT output PLS pulse wave signal
S
1The first sample signal S
2Second sample signal
T
1Time of delay T
2Pulse bandwidth
V
ACInput voltage V
CCSupply voltage
V
INInput V
LIMITThe restriction signal
V
0Output voltage V
PWMSwitch signal
V
SSensing voltage VCC feed end
VS current sense end
Embodiment
Further understand and understanding for the auditor is had architectural feature of the present invention and the effect reached, sincerely help with preferred embodiment and cooperate detailed explanation, illustrate as after:
See also Fig. 2, it is the circuit diagram of switching power converter of the present invention.As shown in the figure, a control circuit 100 comprises a start-up circuit 200, one first comparator 110, one second comparator 120, a NAND gate 160, a rest-set flip-flop 180 and an oscillator 150.Wherein, oscillator 150 provides a pulse wave signal PLS to rest-set flip-flop 180.Based on safety regulation, power converter must be provided with a bleeder resistance (bleedingresistor) 70, the Electromagnetic interference filter (EMIfilter) of the power converter that is used to release.
In order to save power and to reduce number of elements, the present invention further uses bleeder resistance 70 in starting and feedforward compensation.Bleeder resistance 70 is to be coupled to an input voltage V
ACInput V with control circuit 100
INBetween start being used for.One bridge circuit 90, it is coupled to input voltage V
ACAnd between the bleeder resistance 70, bridge circuit 90 more is coupled to the first side winding of a transformer 25.When in case power converter starts, input voltage V
ACCan see through bleeder resistance 70 and be transmitted in start-up circuit 200, and the startup electric capacity 69 that begins to charge, so that a supply voltage V to be provided
CCFeed end VCC to control circuit 100.When the voltage that starts electric capacity 69 reached critical voltage, control circuit 100 can come into operation and export one and switch signal V
PWMThen, the auxiliary winding of transformer 25 can see through a diode 67 and supply voltage V is provided
CC
The restriction signal V that start-up circuit 200 is produced
LIMITIn order to determine a maximum current sensing voltage, it transfers to the positive input terminal of first comparator 110.The positive input terminal of second comparator 120 is back coupling end FB that are coupled to control circuit 100, to be used for the output adjustment of power converter.One optical coupler 55, it is coupled to the secondary side winding of transformer 25 and feedbacks between the end FB, to form a back coupling control loop.The output voltage V of power converter
0See through a Zener diode 51 and a resistance 53 and be sent to optical coupler 55.The secondary side winding of transformer 25 sees through a rectifier 57 and exports this output voltage V
0One filter capacitor 59, it is coupled to the secondary side winding of rectifier 57 and transformer 25.
First comparator 110 is the source electrodes that are coupled in and are connected to through a current sense end VS of control circuit 100 power electric crystal 17 with the negative input end of second comparator 120.The output of first comparator 110 and second comparator 120 is two inputs that are coupled to NAND gate 160 respectively, and the output of NAND gate 160 then is coupled to the replacement end of rest-set flip-flop 180.The output of rest-set flip-flop 180 is coupled to the grid and the output switching signal V of power electric crystal 17
PWMThe source electrode of power electric crystal 17 is coupled to the first side winding of transformer 25.
One switching electric current I P flows through a resistance 19 and causes producing a sensing voltage V at resistance 19
S, first comparator 110 is sensing voltage V relatively
SWith restriction signal V
LIMITVoltage.As sensing voltage V
SGreater than restriction signal V
LIMITVoltage the time, first comparator 110 will be exported the input of the logic signal of a low level to NAND gate 160.Therefore, the logic signal that NAND gate 160 will be exported a high levle to rest-set flip-flop 180 with replacement rest-set flip-flop 180, and forbidden energy switches signal V
PWMAnd then by power electric crystal 17.So, can reach the purpose of restriction power output.
See also Fig. 3, it is the circuit diagram of a preferred embodiment of start-up circuit of the present invention.As shown in the figure, the input V of control circuit 100
INSee through the input voltage V that bleeder resistance 70 is coupled to power converter
ACOne diode 205, it couples the input V of control circuit 100
INWith the feed end VCC of control circuit 100, be used to provide the control circuit 100 of power supply to power converter.One bleeder circuit 207, it comprises resistance 210,220, and resistance 210 is in series with resistance 220.Bleeder circuit 207 sees through a switch 225 and couples input V
INCircuit 230 is preserved in one sampling, and it couples bleeder circuit 207, to take a sample from bleeder circuit 207 and to preserve a voltage signal.One low pass filter 240, it couples sampling and preserves circuit 230, produces a skew signal (offset signal) with the foundation voltage signal.One restricting circuits 250, it couples low pass filter 240, to produce restriction signal V according to a reference signal 260 and skew signal
LIMIT
Restricting circuits 250, it comprises an adder 255 and reference signal 260, and reference signal 260 is coupled to the positive input terminal of adder 255, and the skew signal then is coupled to the negative input end of adder 255.So, restriction signal V
LIMITCan reduce according to the increase of skew signal, to be used for the switch current I of power-limiting transducer
PTherefore, can reach the purpose of feedforward compensation.And, input voltage V
ACDuring increase, be the switch current I that can reduce power converter
PFrom the above, start-up circuit of the present invention is the circuit with detecting, and it is in order to detection lines voltage (line voltage).
Consult Fig. 3 again, sampling is preserved circuit 230 and is comprised one first sampling switch 231 and be coupled to 235 of bleeder circuit 207, the first electric capacity with one first electric capacity, 235, the first sampling switches 231 and be coupled to first sampling switch 231, with the generation voltage signal.First sampling switch 231 is controlled by one first sample signal S
1, it is located away from the switching signal V of power converter
PWMIn addition, the first sample signal S
1Also control switch 225.Low pass filter 240 comprises one second sampling switch 241 and one second electric capacity, 245, the second sampling switches 241 and is coupled to sampling and preserves 245 of first electric capacity, 235, the second electric capacity of circuit 230 and be coupled to second sampling switch 241, to produce the skew signal.Second sampling switch 241 is controlled by one second sample signal S
2, itself and the first sample signal S
1Synchronously.In order to finish low-pass filtering, the capacitance of second electric capacity 245 is the capacitances that are higher than first electric capacity 235.
See also Fig. 4, it is used to produce the first sample signal S for the present invention
1With the second sample signal S
2A circuit diagram that produces circuit.As shown in the figure, the input of a counter 300 is the outputs that couple rest-set flip-flop 180, switches signal V to receive
PWM, the output of counter 300 then is coupled to one and the input of lock 310, and another input of lock 310 also couples the output of rest-set flip-flop 180, switches signal V to receive
PWM, and the output of lock 310 then produces the first sample signal S
1One first one shots (one-shot circuit) 350, it receives the first sample signal S
1, the output of first one shots 350 couples the input of one second one shots 360.Second one shots 360 produces the second sample signal S
2, wherein first one shots 350 as shown in Figure 5, according to the first sample signal S
1Drop edge (falling edge) determine one time of delay T
1, 360 of second one shots determine the second sample signal S
2A pulse bandwidth T
2The first sample signal S
1With the second sample signal S
2Oscillogram as shown in Figure 5.
Comprehensive as can be known aforementioned, restriction signal V
LIMITVoltage be input voltage V
ACA function, and maximum switch current I
PVariation be and input voltage V
ACSide-play amount be inversely proportional to.Low pass filter 240 is filtering input voltage V
ACLine ripple frequently, so bleeder resistance 70 can be used for start-up circuit, to save power.By the resistance value of suitably selecting bleeder resistance 70, can be when low line voltage and the input of high line voltage, for example 90Vac and 264Vac reach consistent restriction power output.
The above, it only is a preferred embodiment of the present invention, be not to be used for limiting scope of the invention process, doing according to the described shape of claim scope of the present invention, structure, feature and spirit such as impartial change and modifies, and all should be included in the interest field of the present invention.
Claims (12)
1, a kind of start-up circuit is characterized in that, it includes:
One input, it sees through the input voltage that a bleeder resistance couples a power converter;
One diode, its couple this input and this power converter a control circuit a feed end and provide power supply to this control circuit;
One bleeder circuit, it sees through a switch and couples this input;
Circuit is preserved in one sampling, and it couples this bleeder circuit, from this bleeder circuit sampling and preservation one voltage signal;
One low pass filter, it couples this sampling and preserves circuit, produces a skew signal according to this voltage signal;
One adder, it couples this low pass filter, produces a restriction signal according to a reference signal and this skew signal;
Wherein, this restriction signal limits a switching electric current of this power converter.
2, start-up circuit as claimed in claim 1 is characterized in that, this bleeder circuit comprises a plurality of resistance that are in series.
3, start-up circuit as claimed in claim 1 is characterized in that, this sampling is preserved circuit and comprised:
One first sampling switch, it couples this bleeder circuit;
One first electric capacity, it couples this first sampling switch, and produces this voltage signal;
Wherein, this first sampling switch is controlled by one first sample signal, and it is located away from one of this power converter and switches signal.
4, start-up circuit as claimed in claim 3 is characterized in that, this low pass filter comprises:
One second sampling switch, it couples this first electric capacity that circuit is preserved in this sampling;
One second electric capacity, it couples this second sampling switch, and produces this skew signal;
Wherein, this second sampling switch is controlled by one second sample signal, and itself and this first sample signal is synchronous.
5, start-up circuit as claimed in claim 4 is characterized in that, the capacitance of this second electric capacity is higher than the capacitance of this first electric capacity.
6, a kind of start-up circuit of tool line detecting voltage is characterized in that it includes:
One input, it sees through the input voltage that a bleeder resistance couples a power converter;
One bleeder circuit, it couples this input;
Circuit is preserved in one sampling, and it couples this bleeder circuit, certainly this bleeder circuit sampling and preservation one voltage signal;
One low pass filter, it couples this sampling and preserves circuit, produces a skew signal according to this voltage signal;
One restricting circuits, it couples this low pass filter, produces a restriction signal according to this skew signal;
Wherein, this restriction signal limits a switching electric current of this power converter.
7, start-up circuit as claimed in claim 6 is characterized in that, this bleeder circuit comprises a plurality of resistance.
8, start-up circuit as claimed in claim 6 is characterized in that, this sampling is preserved circuit and comprised:
One first sampling switch, it couples this bleeder circuit; And
One first electric capacity, it couples this first sampling switch, and produces this voltage signal;
Wherein, this first sampling switch is controlled by one first sample signal, and it is located away from one of this power converter and switches signal.
9, start-up circuit as claimed in claim 8 is characterized in that, this low pass filter includes:
One second sampling switch, it couples this first electric capacity that circuit is preserved in this sampling;
One second electric capacity, it couples this second sampling switch, and produces this skew signal;
Wherein, this second sampling switch is controlled by one second sample signal, and itself and this first sample signal is synchronous.
10, start-up circuit as claimed in claim 9 is characterized in that, the capacitance of this second electric capacity is higher than the capacitance of this first electric capacity.
11, a kind of start-up circuit of tool detecting is characterized in that it includes:
One input, it couples an input voltage of a power converter;
One bleeder circuit, it couples this input;
Circuit is preserved in one sampling, and it couples this bleeder circuit, from this bleeder circuit sampling and preservation one voltage signal; And
One restricting circuits, it produces a restriction signal according to this voltage signal;
Wherein, this restriction signal limits a switching electric current of this power converter.
12, start-up circuit as claimed in claim 11 is characterized in that, this sampling is preserved circuit and comprised:
Switch is preserved in one first sampling, and it couples this bleeder circuit; And
One first electric capacity, it couples this first sampling and preserves switch, and produces this voltage signal;
Wherein, this first sampling is preserved switch and is controlled by one first sample signal, and it is located away from one of this power converter and switches signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006101271862A CN100525025C (en) | 2006-09-12 | 2006-09-12 | Starting circuit with feedforward compensation for power converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006101271862A CN100525025C (en) | 2006-09-12 | 2006-09-12 | Starting circuit with feedforward compensation for power converter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1933306A CN1933306A (en) | 2007-03-21 |
| CN100525025C true CN100525025C (en) | 2009-08-05 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2006101271862A Active CN100525025C (en) | 2006-09-12 | 2006-09-12 | Starting circuit with feedforward compensation for power converter |
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| Country | Link |
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| CN (1) | CN100525025C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10381932B1 (en) | 2018-07-10 | 2019-08-13 | Chicony Power Technology Co., Ltd. | Power conversion device and control method thereof |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8698474B2 (en) * | 2010-06-11 | 2014-04-15 | System General Corp. | Start-up circuit with low standby power loss for power converters |
| US8593833B2 (en) * | 2010-09-07 | 2013-11-26 | System General Corp. | Method and apparatus for a flyback power converter providing output voltage and current regulation without input capacitor |
| CN102447379B (en) * | 2010-10-12 | 2014-06-11 | 日隆电子股份有限公司 | Circuit and method for improving subharmonic of power supply converter |
| JP6443120B2 (en) * | 2015-02-23 | 2018-12-26 | ミツミ電機株式会社 | Power supply control semiconductor device |
| CN106849636B (en) * | 2017-04-13 | 2019-04-12 | 四川长虹电器股份有限公司 | Control circuit for Switching Power Supply |
-
2006
- 2006-09-12 CN CNB2006101271862A patent/CN100525025C/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10381932B1 (en) | 2018-07-10 | 2019-08-13 | Chicony Power Technology Co., Ltd. | Power conversion device and control method thereof |
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| Publication number | Publication date |
|---|---|
| CN1933306A (en) | 2007-03-21 |
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