CN103095103B - Frequency regulation control circuit capable of achieving curvature frequency-reduction with changes of loads in switching power supply - Google Patents

Frequency regulation control circuit capable of achieving curvature frequency-reduction with changes of loads in switching power supply Download PDF

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CN103095103B
CN103095103B CN201310016299.5A CN201310016299A CN103095103B CN 103095103 B CN103095103 B CN 103095103B CN 201310016299 A CN201310016299 A CN 201310016299A CN 103095103 B CN103095103 B CN 103095103B
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module
curvature
frequency
power supply
load
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CN103095103A (en
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田剑彪
朱振东
吴伟江
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SHAOXING DEVECHIP MICROELECTRONICS CO Ltd
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SHAOXING DEVECHIP MICROELECTRONICS CO Ltd
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Abstract

The invention relates to a frequency regulation control circuit capable of achieving curvature frequency-reduction with changes of loads in a switching power supply. The frequency regulation control circuit capable of achieving the curvature frequency-reduction with the changes of the loads in the switching power supply comprises a load detecting module, a under-clocking starting control module, a curvilinear function occurring module and a curvature under-clocking occurring control module. The load detecting module is connected with the curvature under-clocking occurring control module through the under-clocking starting control module and the curvilinear function occurring module in sequence. The frequency regulation control circuit capable of achieving the curvature frequency-reduction with the changes of the loads in the switching power supply is used. When an output signal of the load detecting module is inferior to an under-clocking starting preset voltage, the curvilinear function occurring module is controlled by the work of the under-clocking starting control module to produce a curvilinear function which is relevant to a load condition. Finally, the control of the curvature under-clocking occurring control module work is achieved to produce a frequency changing with the load curve. Thus a fractional load taking into account in the switching power supply and the optimal energy conversion efficiency at the fractional load can be achieved effectively. The frequency regulation control circuit capable of achieving the curvature frequency-reduction with the changes of the loads in the switching power supply is simple and practical in structure, stable and reliable in work performance and wide in application range.

Description

Realize the frequency adjustment control circuit of curvature frequency reducing with load variations in Switching Power Supply
Technical field
The present invention relates to AC/DC switch power technology field, particularly Switching Power Supply is with the frequency adjustment technology field of load variations, specifically refers to the frequency adjustment control circuit structure realizing curvature frequency reducing in a kind of Switching Power Supply with load variations.
Background technology
Prior art major part Switching Power Supply has following three processes substantially with the frequency adjusting method of load variations:
1., when load is heavy duty, Switching Power Supply carries out work with fixing frequency
2., when load is underloading, Switching Power Supply operating frequency is with the linear change of load
3., when load becomes lighter or unloaded, Switching Power Supply enters skip cycle mode and carries out work
Cause the not high reason of conversion efficiency mainly to comprise switching loss and conduction loss by power tube, switching loss refers to that power tube is opened and the loss of shutdown moment generation, the loss that when conduction loss refers to power tube conducting, electric current produces through power tube conducting resistance.
Switching loss is expressed by following formula:
Psw = 1 T ∫ 0 T V gs · I g · dt
Conduction loss is expressed by following formula:
Pon=I 2·R
When during load is in or heavy duty time, flow through power tube current higher, the proportion that conduction loss accounts for overall losses is relatively large; When load is in underloading, the electric current flowing through power tube reduces, and conduction loss proportion reduces to some extent, from above-mentioned switching loss expression formula, if now still adopt higher frequency to carry out work can cause unnecessary switching loss, greatly affect power supply conversion efficiency; When load becomes lighter or unloaded, entering skip cycle mode can reduce switching loss further.
In sum, in carry or heavy duty time the conduction loss proportion that accounts for overall losses comparatively large, during underloading, to account for the proportion of overall losses larger for switching loss.
Currently available technology operating frequency is with the substantially linear change of load variations, according to notebook adapters actual measurement energy conversion efficiency and corresponding frequency data analysis, switching loss accounts for the proportion of overall losses not with the linear change of load, and single linear change frequency reducing curve cannot take into account optimal energy conversion efficiency when middle underloading and underloading simultaneously.
Summary of the invention
The object of the invention is to overcome above-mentioned shortcoming of the prior art, provide a kind of optimal energy conversion efficiency when effectively can take into account underloading and underloading in Switching Power Supply, simple and practical, stable and reliable working performance, the scope of application to realize the frequency adjustment control circuit structure of curvature frequency reducing comparatively widely in Switching Power Supply with load variations.
In order to realize above-mentioned object, the frequency adjustment control circuit structure realizing curvature frequency reducing with load variations in Switching Power Supply of the present invention has following formation:
Realize the frequency adjustment control circuit structure of curvature frequency reducing with load variations in this Switching Power Supply, its main feature is, described circuit structure comprises load detecting module, control module is opened in frequency reducing, curvilinear function generation module and curvature frequency reducing generation control module, and described load detecting module is opened control module by described frequency reducing successively and is connected with described curvature frequency reducing generation control module with curvilinear function generation module.
The load detecting module realized in the frequency adjustment control circuit structure of curvature frequency reducing with load variations in this Switching Power Supply is load voltage state sampling module, and the voltage output end of this load voltage state sampling module is opened control module with described frequency reducing and is connected.
Opening control module with the load variations frequency reducing realized in the frequency adjustment control circuit structure of curvature frequency reducing in this Switching Power Supply is subtractor unit, the voltage output end of described load voltage state sampling module is connected with the first input end of described subtractor unit, second input of described subtractor unit is connected with frequency reducing pattern predeterminated voltage end, and the output of described subtractor unit is connected with described curvilinear function generation module.
The curvilinear function generation module realized in the frequency adjustment control circuit structure of curvature frequency reducing with load variations in this Switching Power Supply comprises multiplier unit and current source, the output of described subtractor unit is connected with the input of described multiplier unit, and the output of this multiplier unit is connected with the control end of described current source, the input of this current source is connected with power supply, and the output of this current source is connected with described curvature frequency reducing generation control module.
The curvature frequency reducing generation control module realized in the frequency adjustment control circuit structure of curvature frequency reducing with load variations in this Switching Power Supply comprises electric capacity, first comparator and the second comparator, the first end ground connection of described electric capacity, second end of this electric capacity is connected with the anode of the second described comparator with the negative terminal of the first described comparator respectively, second end of described electric capacity is connected with power supply with the first constant-current source by the first switch of serial connection successively, and the second end of this electric capacity is successively by the second switch of serial connection, second constant-current source and the 3rd constant-current source ground connection, the output of described current source is connected between the second described constant-current source and the 3rd constant-current source by the 3rd switch, the anode and first of the first described comparator is preset comparative voltage end and is connected, and the output of this first comparator passes through the on off state of the first NAND gate unit and the first switch described in not gate unit controls successively, the negative terminal and second of the second described comparator is preset comparative voltage end and is connected, and the output of this second comparator is connected by the input of the second NAND gate unit with the first described NAND gate unit, the output of this first NAND gate unit is connected with the input of the second described NAND gate unit, and the output of this first NAND gate unit control described in second switch and the on off state of the 3rd switch.
Have employed the frequency adjustment control circuit structure realizing curvature frequency reducing in the Switching Power Supply of this invention with load variations, owing to wherein detecting load status by load detecting module, when load detecting module output signal opens predeterminated voltage lower than frequency reducing, frequency reducing is opened control module job control curvilinear function generation module and is produced the curvilinear function relevant to load condition, final realization controls the frequency of curvature frequency reducing generation module work generation with load curve change, thus the optimal energy conversion efficiency achieved when effectively taking into account underloading and underloading in Switching Power Supply, and it is simple and practical, stable and reliable working performance, the scope of application is comparatively extensive.
Accompanying drawing explanation
Fig. 1 is the curvature frequency reducing control principle schematic diagram of the frequency adjustment control circuit structure realizing curvature frequency reducing in Switching Power Supply of the present invention with load variations.
Fig. 2 realizes with load variations the saw-toothed oscillator schematic diagram that the constant-current source in the frequency adjustment control circuit structure of curvature frequency reducing produces capacitor charge and discharge in Switching Power Supply of the present invention.
Fig. 3 realizes the concrete control principle drawing of curvature frequency reducing in the frequency adjustment control circuit structure of curvature frequency reducing with load variations in Switching Power Supply of the present invention.
Fig. 4 realizes the frequency curve of the frequency adjustment control circuit structure of curvature frequency reducing with load variations schematic diagram with load variations in Switching Power Supply of the present invention.
Embodiment
In order to more clearly understand technology contents of the present invention, describe in detail especially exemplified by following examples.
Refer to shown in Fig. 1, the load detecting module realized in the frequency adjustment control circuit structure of curvature frequency reducing with load variations in this Switching Power Supply is load voltage state sampling module 300, and the voltage output end of this load voltage state sampling module 300 is opened control module with described frequency reducing and is connected.
Wherein, it is subtractor unit 301 that control module is opened in described frequency reducing, the voltage output end of described load voltage state sampling module 300 is connected with the first input end of described subtractor unit 301, second input of described subtractor unit 301 is connected with frequency reducing pattern predeterminated voltage end Vref3, and the output of described subtractor unit 301 is connected with described curvilinear function generation module.
Simultaneously, described curvilinear function generation module comprises multiplier unit 302 and current source 303, the output of described subtractor unit 301 is connected with the input of described multiplier unit 302, and the output of this multiplier unit 302 is connected with the control end of described current source 303, the input of this current source 303 is connected with power supply, and the output of this current source 303 is connected with described curvature frequency reducing generation control module.
Moreover, described curvature frequency reducing generation control module comprises electric capacity 310, first comparator 311 and the second comparator 312, the first end ground connection of described electric capacity 310, second end of this electric capacity 310 is connected with the anode of the second described comparator 312 with the negative terminal of the first described comparator 311 respectively, second end of described electric capacity 310 is connected with power supply with the first constant-current source 305 by the first switch 306 of serial connection successively, and the second end of this electric capacity 310 is successively by the second switch 307 of serial connection, second constant-current source 308 and the 3rd constant-current source 309 ground connection, the output of described current source 303 is connected between the second described constant-current source 308 and the 3rd constant-current source 309 by the 3rd switch 304, the anode and first of the first described comparator 311 is preset comparative voltage end Vref1 and is connected, and the output of this first comparator 311 passes through the on off state of the first NAND gate unit and the first switch 306 described in not gate unit controls successively, the negative terminal and second of the second described comparator 312 is preset comparative voltage end Vref2 and is connected, and the output of this second comparator 312 is connected by the input of the second NAND gate unit with the first described NAND gate unit, the output of this first NAND gate unit is connected with the input of the second described NAND gate unit, and the output of this first NAND gate unit control described in second switch 307 and the on off state of the 3rd switch 304.
In the middle of reality uses, refer to shown in Fig. 1, wherein for curvature frequency reducing controls schematic diagram, load status is detected by load detecting module 100, when load detecting module 100 output signal open predeterminated voltage lower than frequency reducing time, frequency reducing is opened control module 101 job control curvilinear function generation module 102 and is produced the curvilinear function relevant to load condition, and the work of final control curvature frequency reducing generation module 103 produces the frequency with load curve change.
Refer to again shown in Fig. 2, it is the saw-toothed oscillator that constant-current source produces capacitor charge and discharge, its operation principle is: initial condition electric capacity 204 level equals the second comparator 206 and presets comparative level Vref2, logical signal X controls second switch 202 and disconnects, meanwhile logical signal Y controls the first switch 201 and closes, first constant-current source 200 pairs electric capacity 204 charges, when electric capacity 204 level reach the first comparator 205 preset comparative level Vref1 time, logical signal Y controls the first switch 201 and disconnects, meanwhile logical signal X control second switch 202 closes, second constant-current source 203 pairs electric capacity 204 discharges until level drops to the second comparator 206 preset comparative level Vref2, so far complete cycle of oscillation is completed, charging interval:
Tr=C(Vref1-Vref2)/I 201
Discharge time:
Tf=C(Vref1-Vref2)/I 203
Therefore this sawtooth oscillation cycle:
T=Tr+Tf=C(Vref1-Vref2)/I 201+C(Vref1-Vref2)/I 203
Fig. 3 is curvature frequency reducing control principle schematic diagram, its principle is: when load lightens, load condition sampled signal Vs is obtained by load detecting module 300, when sampled signal Vs is lower than frequency reducing pattern preset value Vref3, sampled signal VS and frequency reducing preset value Vref3 does after subtraction through subtracter block 301 and does multiplying through multiplication module 302 again, signal controlling current source 303 after computing produce relevant to load become the electric current of parabolic increase:
I 303=K×(Vs-Vref) 2
Oscillator is initial, logical signal X controls second switch 307 and the 3rd switch 304 disconnects, meanwhile logical signal Y controls the first switch 306 and closes, constant-current source 305 pairs of electric capacity 310 charge, when electric capacity 310 level reach the first comparator 311 preset comparative level time, logical signal Y controls the first switch 306 and disconnects, meanwhile logical signal X control second switch 307 and the 3rd switch 304 close, constant-current source 308 pairs of electric capacity 310 discharge until electric capacity 310 level drops to the second comparator 312 preset comparative level, and discharging current is now:
I 308=I 309-I 303=I 309-K×(Vs-Vref) 2
This electric current becomes parabola to change with load, has following relation:
Tr=C(Vref1-Vref2)/I 305
Tf=C(Vref1-Vref2)/I 308=C(Vref1-Vref2)/(I 309-K×(Vs-Vref) 2);
Cycle of oscillation:
T=C(Vref1-Vref2)/I 305+C(Vref1-Vref2)/(I 309-K×(Vs-Vref) 2);
Can know from expression formula, along with load lighten gradually concussion cycle T increase with curve form, namely frequency reduces with curve form.
Have employed the frequency adjustment control circuit structure realizing curvature frequency reducing in above-mentioned Switching Power Supply with load variations, owing to wherein detecting load status by load detecting module, when load detecting module output signal opens predeterminated voltage lower than frequency reducing, frequency reducing is opened control module job control curvilinear function generation module and is produced the curvilinear function relevant to load condition, final realization controls the frequency of curvature frequency reducing generation module work generation with load curve change, thus the optimal energy conversion efficiency achieved when effectively taking into account underloading and underloading in Switching Power Supply, and it is simple and practical, stable and reliable working performance, the scope of application is comparatively extensive.
In this description, the present invention is described with reference to its specific embodiment.But, still can make various amendment and conversion obviously and not deviate from the spirit and scope of the present invention.Therefore, specification and accompanying drawing are regarded in an illustrative, rather than a restrictive.

Claims (3)

1. the frequency adjustment control circuit structure of curvature frequency reducing in a Switching Power Supply, is realized with load variations, it is characterized in that, described circuit structure comprises load detecting module, control module is opened in frequency reducing, curvilinear function generation module and curvature frequency reducing generation control module, and described load detecting module is opened control module by described frequency reducing successively and is connected with described curvature frequency reducing generation control module with curvilinear function generation module;
Described load detecting module is load voltage state sampling module (300), and the voltage output end of this load voltage state sampling module (300) is opened control module with described frequency reducing and is connected;
It is subtractor unit (301) that control module is opened in described frequency reducing, the voltage output end of described load voltage state sampling module (300) is connected with the first input end of described subtractor unit (301), second input of described subtractor unit (301) is connected with frequency reducing pattern predeterminated voltage end (Vref3), and the output of described subtractor unit (301) is connected with described curvilinear function generation module.
2. the frequency adjustment control circuit structure of curvature frequency reducing in Switching Power Supply according to claim 1, is realized with load variations, it is characterized in that, described curvilinear function generation module comprises multiplier unit (302) and current source (303), the output of described subtractor unit (301) is connected with the input of described multiplier unit (302), and the output of this multiplier unit (302) is connected with the control end of described current source (303), the input of this current source (303) is connected with power supply, and the output of this current source (303) is connected with described curvature frequency reducing generation control module.
3. the frequency adjustment control circuit structure of curvature frequency reducing in Switching Power Supply according to claim 2, is realized with load variations, it is characterized in that, described curvature frequency reducing generation control module comprises electric capacity (310), first comparator (311) and the second comparator (312), the first end ground connection of described electric capacity (310), second end of this electric capacity (310) is connected with the anode of described the second comparator (312) with the negative terminal of described the first comparator (311) respectively, second end of described electric capacity (310) is connected with power supply with the first constant-current source (305) by first switch (306) of serial connection successively, and second end of this electric capacity (310) is successively by the second switch (307) of serial connection, second constant-current source (308) and the 3rd constant-current source (309) ground connection, the output of described current source (303) is connected between described the second constant-current source (308) and the 3rd constant-current source (309) by the 3rd switch (304), the anode and first of described the first comparator (311) is preset comparative voltage end (Vref1) and is connected, and the output of this first comparator (311) passes through the on off state of the first NAND gate unit and the first switch (306) described in not gate unit controls successively, the negative terminal and second of described the second comparator (312) is preset comparative voltage end (Vref2) and is connected, and the output of this second comparator (312) is connected by the input of the second NAND gate unit with the first described NAND gate unit, the output of this first NAND gate unit is connected with the input of the second described NAND gate unit, and the output of this first NAND gate unit control described in second switch (307) and the on off state of the 3rd switch (304).
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CN103607112B (en) * 2013-12-01 2016-03-02 西安电子科技大学 Frequency of adaptive switch Circuit tuning
CN103605035B (en) * 2013-12-02 2016-06-08 绍兴光大芯业微电子有限公司 The no load detection circuit structure of self-adaption switch electric power source
CN104467365B (en) * 2014-12-19 2017-06-27 青岛歌尔声学科技有限公司 Power supply conversion efficiency indication signal produces circuit and power supply conversion efficiency adjustment circuit
CN113098272A (en) * 2021-04-23 2021-07-09 陕西亚成微电子股份有限公司 Control method and circuit of switching power supply

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CN101316114A (en) * 2008-07-09 2008-12-03 华为技术有限公司 Spread-spectrum modulation circuit, variable frequency triangular-wave generator and signal processing method
CN101335488A (en) * 2007-06-29 2008-12-31 天钰信息科技(上海)有限公司 System for modulating working frequency of switch power source converter

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