CN104009626A - Feedback circuit for current feedback type DC-DC converter - Google Patents
Feedback circuit for current feedback type DC-DC converter Download PDFInfo
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- CN104009626A CN104009626A CN201410243353.4A CN201410243353A CN104009626A CN 104009626 A CN104009626 A CN 104009626A CN 201410243353 A CN201410243353 A CN 201410243353A CN 104009626 A CN104009626 A CN 104009626A
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Abstract
The invention relates to an electronic circuit technology, in particular to a feedback circuit for a current feedback type DC-DC converter. The feedback circuit for the current feedback type DC-DC converter is characterized by comprising a first comparator COMP1, a second comparator COMP2, a subtractor and an RS trigger, the positive input end of the first comparator COMP1 is connected with feedback currents, the negative phase input end of the first comparator COMP1 is connected with first reference currents Iref1, the output end of the first comparator COMP1 is connected with the R end of the RS trigger, the positive input end of the subtractor is connected with the first reference currents Iref1, the negative input end of the subtractor is connected with second reference currents Iref1, the positive input end of the second comparator COMP2 is connected with the output end of the subtractor, the negative phase input end of the second comparator COMP2 is connected with the feedback currents, and the output end of the second comparator COMP2 is connected with the S end of the RS trigger. The feedback circuit has the advantages that the peak value and the valley value of the feedback currents in each period are limited, and therefore generation of the non-linear phenomena such as diverging and chaos is limited. The feedback circuit is particularly suitable for the current feedback type DC-DC converter.
Description
Technical field
The invention belongs to electronic circuit technology, relate to specifically a kind of feedback circuit for current feedback DC-DC converter.
Background technology
Existence due to inductance capacitance and switching over, Switching Power Supply itself is exactly a kind of strongly non-linear system, simultaneously, these non-linear natures make power system analysis and control method become very unreliable, and have rich and varied non-linear phenomena, and these non-linear phenomenas will affect the overall performance of DC-DC converter.In the middle of Practical Project, should avoid the generation of these forks, chaos phenomenon as far as possible.
Peak current feedback and valley point current feedback are that order first two is applied more feedback mode control, all that inductive current sampling is fed back to and is input to the switch that driving signal that logical block produces certain duty ratio carrys out driving switch pipe after comparing with reference current in comparator, as shown in Figure 2.Difference is, in peak current feedback the positive input of sampled inductance current value input comparator with reference to peak value current value ratio, and in valley point current feedback sampled inductance current value be input to '-' end of comparator with reference to valley current value comparison.In two kinds of feedback systems, all will use ON time control unit, i.e. pulse square wave CLK, limits the operating frequency of system.
The switch converters of peak current feedback and valley point current feedback model is non-linear variable structure control system, the conducting of power switch pipe or shutoff are periodically switched system in different structures, cause like this switch converters to there is complicated non-linear behavior, the multiple fork roads that leads to chaos such as period doubling bifurcation, Hopf fork, Flip fork, border collision bifurcation, subharmonic oscillation, frequency reducing and low-frequency fluctuation phenomenon etc.
Application number is: in the Chinese patent of CN201210351869.1, mention and feedback current value is accessed after comparator is relatively exported to rest-set flip-flop and carry out logical operation, in conjunction with pulse width control module and reverser, reach fixing method deadline again, but this feedback system fails to control the stability that chaos improves changer system.
Application number is: in the Chinese patent of CN201210288345.2, mention by feedback voltage value and replace the method for CLK signal input rest-set flip-flop logical block to avoid producing subharmonic oscillation, produce the object of bifurcation chaos phenomenon.But can only directly regulate current peak, to valley, adjustment needs the variation of other parts of system indirectly to control, so corresponding speed is slower.
In the middle of peak current feedback, because state switching instant is that feedback current value is while equaling reference current value, so current peak is constant in each cycle, but electric current valley is not restriction really, variation along with circuit parameter, electric current valley is likely unequal, and this has just caused the generation of the non-linear phenomenas such as fork, chaos.By contrast, in the middle of valley point current feedback, electric current valley is constant in each cycle, but really not restriction of current peak, along with the variation of circuit parameter, current peak is likely unequal, and this has also caused the generation of the non-linear phenomenas such as fork, chaos.
Summary of the invention
Object of the present invention, is exactly the problem existing for above-mentioned conventional art, proposes the feedback circuit that a kind of combination peak current feedback loop for current feedback DC-DC converter and valley point current feedback loop strengthen changer system stability.
The present invention solves the problems of the technologies described above adopted technical scheme: a kind of feedback circuit for current feedback DC-DC converter, comprise DC-DC converter, it is characterized in that, also comprise the first comparator C OMP1, the second comparator C OMP2, subtracter and rest-set flip-flop; Wherein, the positive input of the first comparator C OMP1 connects the feedback current of DC-DC converter output, and its negative-phase input meets the first reference current Iref1, the R end of its output termination rest-set flip-flop; The positive input termination first reference current Iref1 of subtracter, its negative input termination the second reference current Iref1; The positive input of the second comparator C OMP2 connects the output of subtracter, and its negative-phase input connects the feedback current of DC-DC converter output, the S end of its output termination rest-set flip-flop; The input of the output termination DC-DC converter of rest-set flip-flop.
Beneficial effect of the present invention is, combine the features of peak current feedback and valley point current feedback, omit the ON time control unit of traditional circuit and middle employing, and being divided into feedback current peak value, state switching instant equals the value of reference current 1 and the value that feedback current valley equals reference current 2, the peak value of each cycle internal feedback electric current and valley are limited, thereby limited the generation of the non-linear phenomenas such as fork, chaos.
Accompanying drawing explanation
Fig. 1 is the feedback circuit structure schematic diagram for current feedback DC-DC converter of the present invention;
Fig. 2 is peak value feedback-type and valley feedback-type DC-DC converter topology structural representation;
Fig. 3 is the current feedback buck-boost transformer configuration schematic diagram that peak value feedback provided by the invention and valley feedback combine;
Fig. 4 is that peak value feedback provided by the invention and valley feed back inductive current time domain waveform schematic diagram in the current feedback DC-DC converter combining;
Fig. 5 is for take reference electric current I ref1 as fork parameter, the inductive current bifurcation graphs of buck-boost converter under peak current FEEDBACK CONTROL;
Fig. 6 is for take reference electric current I ref1 as fork parameter, the inductive current bifurcation graphs of buck-boost converter under valley point current FEEDBACK CONTROL;
Fig. 7 is for take reference electric current I ref1 as fork parameter, the inductive current bifurcation graphs of buck-boost converter under Current Feedback Control provided by the invention;
Fig. 8 is that the value of reference current Iref1 is the comparison of wave shape figure of inductive current and switching signal in 0.1 o'clock valley point current feedback and current feedback DC-DC converter provided by the invention;
Fig. 9 is that the value of reference current Iref1 is the comparison of wave shape figure of inductive current and switching signal in 0.4 o'clock valley point current feedback and current feedback DC-DC converter provided by the invention;
Figure 10 is that the value of reference current Iref1 is the comparison of wave shape figure of inductive current and switching signal in 0.8 o'clock peak current feedback and current feedback DC-DC converter provided by the invention;
Figure 11 is that the value of reference current Iref1 is the comparison of wave shape figure of inductive current and switching signal in 1.5 o'clock peak currents feedback and current feedback DC-DC converter provided by the invention.
Embodiment
Below in conjunction with accompanying drawing, describe technical scheme of the present invention in detail
As shown in Figure 1, the feedback circuit for current feedback DC-DC converter of the present invention, is characterized in that, comprises the first comparator C OMP1, the second comparator C OMP2, subtracter and rest-set flip-flop; Wherein, the positive input of the first comparator C OMP1 connects feedback current, and its negative-phase input meets the first reference current Iref1, the R end of its output termination rest-set flip-flop; The positive input termination first reference current Iref1 of subtracter, its negative input termination the second reference current Iref1; The positive input of the second comparator C OMP2 connects the output of subtracter, and its negative-phase input connects feedback current, the S end of its output termination rest-set flip-flop.
Operation principle of the present invention is:
The first comparator C OMP1 is the part in peak current feedback loop, i.e. feedback current value input comparator positive input.As feedback current value i
l1while being greater than Iref1, the first comparator C OMP1 is output as 1; As feedback current value i
l1while being less than Iref1, comparator is output as 0.The second comparator C OMP2 is the part in valley point current feedback loop, i.e. feedback current value input comparator negative-phase input.As feedback current value i
l1while being greater than Iref1-Iref2, the second comparator C OMP2 is output as 0; As feedback current value i
l1while being less than Iref1-Iref2, the second comparator C OMP2 is output as 1.The output of the first comparator C OMP1 connects rest-set flip-flop R end; The output of the second comparator C OMP2 connects rest-set flip-flop S end.From rest-set flip-flop logic, R end becomes at 1 o'clock from 0, and trigger output Q is 0, and switching tube is closed; When S holds by 0 change 1, trigger output Q is 1, switching tube conducting.So switch of the output control switch pipe of two comparators.When the first comparator C OMP1 is output as 1, i.e. feedback current value i
l1while being greater than Iref1, switching tube is closed; The second comparator C OMP2 is output as at 1 o'clock, i.e. feedback current value i
l1while being less than Iref1-Iref2, switching tube is open-minded.
In current feedback buck-boost circuit, as shown in Figure 3, during switching tube conducting, induction charging, inductive current is linear to rise, and the rate of rise is
when inductive current rises to Iref1, switching tube is closed, and inductance is to load discharge, and inductive current declines, and descending slope is
therefore, feedback inductance electric current has Iref1 and two limit values of Iref1-Iref2, and system cycle is
Wherein Iref1 and Iref2 are reference current value, and L is inductance sizes values, and Uin is input voltage, and U0 is output voltage, as shown in Figure 4.
Take reference current Iref1 as fork parameter, can obtain peak current feedback, valley point current feedback, both are in conjunction with the bifurcation graphs of the DC-DC changer system under current feedback.As shown in Figure 5, can see, in the middle of peak current feedback, the value of reference current Iref1 is less than at 0.8 o'clock, and system is in stable state; The value of reference current Iref1 is greater than at 0.8 o'clock, and system is in unsettled fork and chaos state.In the middle of valley point current feedback, the value of reference current Iref1 is greater than at 0.42 o'clock, and system is in stable state; The value of reference current Iref1 is less than at 0.42 o'clock, and system is in unsettled fork and chaos state.And in the middle of the current feedback of both combinations that the present invention is proposed, reference current Iref1 is in 0 to 1.5 scope, system is all the time in stable state.From the further proof system status of the time domain waveform figure of inductive current.As shown in Figure 6, for the value of reference current Iref1 is 0.1 o'clock valley point current feedback and in conjunction with the comparison of wave shape figure of inductive current in current feedback and switching signal.Can find out, valley point current reponse system is in chaos state, and in conjunction with current feedback system in stable state.As shown in Figure 7, for the value of reference current Iref1 is 0.4 o'clock valley point current feedback and in conjunction with the comparison of wave shape figure of inductive current in current feedback and switching signal.Can find out, valley point current reponse system is in two times of fork states, and in conjunction with current feedback system in stable state.As shown in Figure 8, for the value of reference current Iref1 is 0.8 o'clock peak current feedback and in conjunction with the comparison of wave shape figure of inductive current in current feedback and switching signal.Can find out, peak current reponse system is in two times of fork states, and in conjunction with current feedback system in stable state.As shown in Figure 9, for the value of reference current Iref1 is 1.5 o'clock peak current feedbacks and in conjunction with the comparison of wave shape figure of inductive current in current feedback and switching signal.Can find out, peak current reponse system is in chaos state, and in conjunction with current feedback system in stable state.
Claims (1)
1. for a feedback circuit for current feedback DC-DC converter, comprise DC-DC converter, it is characterized in that, also comprise the first comparator C OMP1, the second comparator C OMP2, subtracter and rest-set flip-flop; Wherein, the positive input of the first comparator C OMP1 connects the feedback current of DC-DC converter output, and its negative-phase input meets the first reference current Iref1, the R end of its output termination rest-set flip-flop; The positive input termination first reference current Iref1 of subtracter, its negative input termination the second reference current Iref1; The positive input of the second comparator C OMP2 connects the output of subtracter, and its negative-phase input connects the feedback current of DC-DC converter output, the S end of its output termination rest-set flip-flop; The input of the output termination DC-DC converter of rest-set flip-flop.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410243353.4A CN104009626A (en) | 2014-06-04 | 2014-06-04 | Feedback circuit for current feedback type DC-DC converter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410243353.4A CN104009626A (en) | 2014-06-04 | 2014-06-04 | Feedback circuit for current feedback type DC-DC converter |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050212499A1 (en) * | 2004-03-29 | 2005-09-29 | Fujitsu Limited | Switching regulator control circuit, switching regulator and switching regulator control method |
| CN102223067A (en) * | 2011-06-09 | 2011-10-19 | 许瑞清 | Device and method for driving constant-current source load |
| CN103220859A (en) * | 2013-04-12 | 2013-07-24 | 深圳市明微电子股份有限公司 | Constant-current control circuit and device with same |
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2014
- 2014-06-04 CN CN201410243353.4A patent/CN104009626A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050212499A1 (en) * | 2004-03-29 | 2005-09-29 | Fujitsu Limited | Switching regulator control circuit, switching regulator and switching regulator control method |
| CN102223067A (en) * | 2011-06-09 | 2011-10-19 | 许瑞清 | Device and method for driving constant-current source load |
| CN103220859A (en) * | 2013-04-12 | 2013-07-24 | 深圳市明微电子股份有限公司 | Constant-current control circuit and device with same |
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Application publication date: 20140827 |