Background technology
DC converter is a kind ofly to convert direct current energy the converter of another kind of or multiple direct current energy to, is the critical piece of direct-current switch power supply.Along with the develop rapidly of power electronic technology, be that the direct-current switch power supply of core is used more and more widely with the DC converter.DC converter comprises various topological structures such as step-down type dc converter, booster type DC converter, buck-boost type DC converter and inverse-excitation type DC converter.
With reference to figure 1, Fig. 1 is the control circuit structural representation of step-down type dc converter common in the prior art.R among the figure
1And R
2Form bleeder circuit, output voltage V
oAfter said bleeder circuit dividing potential drop, obtain an output voltage feedback signal FB, said output voltage feedback signal FB and reference voltage V
RefRelatively again by capacitor C
2Compensate, obtain the reference voltage V of this control circuit
C-ref, the reference voltage V of this control circuit
C-refWith said output voltage feedback signal FB compare the control signal D of back through the switch in the rest-set flip-flop output main circuit with
In DC converter, inductive current i
LThe AC portion output capacitance C that mainly flows through
o, capacitor C
oEquivalent resistance R
CoOn voltage V
RcoBe inductive current i
LAC portion and equivalent resistance R
CoProduct, therefore, said voltage V
RcoWith inductive current i
LSo the proportional relation of ripple is voltage V
RcoThe variation tendency of waveform and inductive current i
LAlso be consistent.Again because output voltage V
oBe capacitor C
oOn voltage V
CoWith capacitor C
oEquivalent resistance R
CoOn voltage V
RcoSum is with reference to figure 2, therefore in output voltage V
oIn in fact comprised inductive current i
LInformation.
For equivalent resistance R
CoBigger output capacitance C
o, output voltage V
oMainly by equivalent resistance R
CoOn voltage V
RcoDecision, system can steady operation and the response of acquisition Fast Dynamic.As said equivalent resistance R
CoHour, output voltage V
oMainly by output capacitance C
oThe voltage V at two ends
CoDecision is because voltage V
CoWith respect to V
RcoPhase lag, subharmonic oscillation may appear in system, so the stability of system is confined to employed output capacitance C
oCharacteristic.Simultaneously, for the modulation system of deciding frequency, when duty ratio near or greater than 50 percent the time, system also subharmonic oscillation can occur.
To the problems referred to above, the method that proposes a kind of slope compensation in the prior art is improved, referring to Fig. 3.Output voltage feedback signal FB and a slope compensation signal addition, through suitable slope compensation, system can not occur subharmonic oscillation because duty ratio increases.But as output capacitance C
oEquivalent resistance R
CoHour, the current information that is comprised among the output voltage feedback signal FB seldom, in this case; Only through increasing slope compensation, though can let system get into the stable operation situation, the stability margin of system is very little; When the load saltus step occurring, output voltage V
oVibration very easily appears.
Summary of the invention
In view of this, the present invention provides a kind of compensation control circuit and method of DC converter, when adding slope compensation the inductive current in the main circuit is sampled, and is prone to the problem of subharmonic oscillation with resolution system, and improves stability margin.
For realizing above-mentioned purpose, the present invention provides following technical scheme:
A kind of compensation control circuit of DC converter is used for the switch motion of the switching tube of DC inverter main circuit is controlled, and this compensation control circuit comprises:
The output voltage feedback circuit, it receives the output voltage of said main circuit, and exports an output voltage feedback signal;
The inductive current sample circuit, it is sampled to the inductive current in the main circuit, with output sample rate current signal;
Ramp signal generation circuit produces a ramp signal;
First control unit, it receives the signal and first reference voltage signal after said output voltage feedback signal, sample rate current signal and the ramp signal addition, and compares to export first control signal;
Second control unit, it exports second control signal, controls said DC converter and is operated in variable mode or fixed pattern frequently;
Switching signal generation circuit, it receives said first control signal and second control signal, with the switch controlling signal of the switching tube in the output main circuit.
Preferably; In the above-mentioned compensation control circuit, said inductive current sample circuit carries out analog sampling or its set time point is carried out digital sample obtaining said sample rate current signal to said inductive current ascent stage or the set time section in the decline stage in each switch periods.
Preferably; In the above-mentioned compensation control circuit, said first reference voltage signal is a preset reference voltage signal or is said output voltage feedback signal and the preset reference voltage signal error amplification signal that produces of the back signal of gained after compensating again relatively.
Preferably, in the above-mentioned compensation control circuit, said second control unit comprises any in clock generating circuit, constant ON time control circuit and the constant turn-off time control circuit.
Preferably; In the above-mentioned compensation control circuit; Said first control unit comprises a comparator, and its input receives the signal and first reference voltage signal after said output voltage feedback signal, sample rate current signal and the ramp signal addition, and output is exported said first control signal.
Preferably, in the above-mentioned compensation control circuit, said switching signal generation circuit comprises a rest-set flip-flop, and its input receives said first control signal and second control signal, the switch controlling signal of the switching tube in its output output main circuit.
Preferably, in the above-mentioned compensation control circuit, the topological structure of said main circuit is step-down type dc converter, booster type DC converter, buck-boost type DC converter or inverse-excitation type DC converter.
The present invention also provides a kind of compensating control method of DC converter, and to realize the control to the switching tube switch motion in the DC inverter main circuit, this compensating control method comprises:
Obtain an output voltage feedback signal after the output voltage of main circuit handled;
Inductive current in the main circuit is sampled, to obtain the sample rate current signal;
Produce a ramp signal;
With said output voltage feedback signal, sample rate current signal and ramp signal addition, the signal and first reference voltage signal after the addition are compared, export first control signal;
Export second control signal, control said DC converter and be operated in variable mode or fixed pattern frequently;
According to said first control signal and second control signal, the switch controlling signal of the switching tube in the output main circuit.
Preferably, in the above-mentioned compensating control method, the inductive current in the main circuit is sampled,, specifically comprises to obtain the sample rate current signal:
In each switch periods inductive current ascent stage in the main circuit or the set time section in the decline stage are carried out analog sampling or its set time point is carried out digital sample, to obtain the sample rate current signal.
Preferably, in the above-mentioned compensating control method, the topological structure of said main circuit is step-down type dc converter, booster type DC converter, buck-boost type DC converter or inverse-excitation type DC converter.
Can find out that from technique scheme the compensation control circuit of DC converter provided by the present invention is through the information that adds slope compensation and in control procedure, add inductive current; Even for the less system of the equivalent resistance of output capacitance; The information that comprises enough sign inductive currents in the control circuit makes the system can stable operation and heighten its stability margin, in the process of dynamic response; System is not easy vibration; And further guarantee the Fast Dynamic response, and having improved the circuit control performance, the stability of system also no longer is confined to the characteristic of employed output capacitance.Because the inductive current information in the main circuit can obtain from inductance or switching tube sampling, therefore, this compensation control circuit does not receive the influence of switching noise in implementation process in addition.
Embodiment
For the purpose, technical scheme and the advantage that make the embodiment of the invention clearer; To combine the accompanying drawing in the embodiment of the invention below; Technical scheme in the embodiment of the invention is carried out clear, intactly description; Obviously, described embodiment is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills are not making the every other embodiment that is obtained under the creative work prerequisite, all belong to the scope of the present invention's protection.
Embodiment one
With reference to figure 4, be depicted as structural representation according to first embodiment of the compensation control circuit of DC converter of the present invention; Topological structure with main circuit is that the step-down type dc converter is that example describes, and the compensation control circuit of this DC converter comprises:
The output voltage feedback circuit, it receives the output voltage V of said main circuit
o, and export an output voltage feedback signal FB;
The inductive current sample circuit, it is sampled to the inductive current in the main circuit, with output sample rate current signal;
Ramp signal generation circuit produces a ramp signal;
First control unit, it receives the signal and the first reference voltage signal V after said output voltage feedback signal FB, sample rate current signal and the ramp signal addition
Ref1, and compare to export first control signal;
Second control unit, it exports second control signal, controls said DC converter and is operated in variable mode or fixed pattern frequently;
Switching signal generation circuit; It receives said first control signal and second control signal, with the action of output switch control signal D switching tube in the control main circuit with
.
From embodiment illustrated in fig. 4, can find out, in the control procedure to DC converter, not only add slope compensation control; Through sampling, also added the information that characterizes inductive current, even for the less system of the equivalent resistance of output capacitance to inductive current; The information that comprises enough sign inductive currents in the control circuit makes the system can stable operation and heighten its stability margin, in the process of dynamic response; System is not easy vibration; And further guarantee the Fast Dynamic response, and having improved the circuit control performance, the stability of system no longer is confined to the characteristic of employed output capacitance.
In practical application; Can select the inductive current ascent stage in the main circuit according to the concrete mode of operation of control circuit still is that the signal of decline stage is sampled, and when being operated in peak control mode like control circuit, needs the information of inductive current ascent stage; Therefore the inductive current sample circuit need be sampled to the signal of inductive current ascent stage; And control circuit is corresponding when being operated in the valley control model, need sample to the signal of inductive current decline stage.
Embodiment two
With reference to figure 5, be the compensation control circuit structural representation of a kind of DC converter provided by the present invention, be that the step-down type dc converter is that example describes still wherein with the topological structure of main circuit.
The feedback circuit of output voltage described in the present embodiment comprises by resistance R
1And R
2The bleeder circuit that is composed in series, the output voltage V of main circuit
oAfter bleeder circuit carries out dividing potential drop, in resistance R
1And R
2Points of common connection export an output voltage feedback signal FB.
Said inductive current sample circuit can carry out analog sampling to inductive current ascent stage or the set time section in the decline stage in each switch periods; Also can in each switch periods, carry out digital sample to inductive current ascent stage or the point of the set time in the decline stage; Can select signal that sampling obtains and sampling coefficients R according to actual conditions
iProduct form said sample rate current signal.The rate of rise of the inductive current in the main circuit does
Its descending slope does
V wherein
In, V
oBe respectively the input voltage and the output voltage of main circuit, during the analog signal of the inductive current of then sampling, the inductive current ascent stage sampled, the rate of rise of said sample rate current signal is R
iS
n, the inductive current decline stage to be sampled, said sample rate current signal descending slope is R
iS
fDuring the digital signal of sampling inductive current, in each switch periods as required to inductive current ascent stage or the current value of the set time point maintenance of sampling in the decline stage, if the inductive current value of this sampled point is i
L *, then the said sample rate current signal of the output in each cycle is R
iI
L *Digital signal with the sampling inductive current is that example describes in the present embodiment.
Said ramp signal generation circuit produces a ramp signal.
First control unit comprises a comparator described in the present embodiment, and its in-phase input end receives the signal after said output voltage feedback signal FB, sample rate current signal and the ramp signal addition, and inverting input receives the said first reference voltage signal V
Ref1, its output is exported the comparison signal of the two as said first control signal.
Said second control unit comprises a clock signal generating circuit, and the certain clock signal frequently of its output is as said second control signal, controls said step-down type dc converter and is operated in and decides the frequency pattern.
Said switching signal generation circuit comprises a rest-set flip-flop; Its R termination is received said first control signal; The S termination is received said second control signal, and Q end and
end difference output switch control signal D and
are with the action of the switching tube in the control main circuit.
Specify the course of work of control circuit below in conjunction with the working waveform figure of embodiment among Fig. 5 shown in Figure 6.Still the digital signal with sampling inductive current ascent stage is an example, and to the maintenance of sampling of the current value of inductive current ascent stage set time point, the inductive current value of this sampled point is i to said inductive current sample circuit in each switch periods
L *, then the output sample rate current signal in each cycle of inductive current sample circuit is R
iI
L *, said ramp signal generation circuit produces a ramp signal Ramp; With above-mentioned sample rate current signal R
iI
L *, the signal behind these three signal plus of ramp signal Ramp and output voltage feedback signal FB is through comparator and the said first reference voltage signal V
Ref1Compare, when its greater than the said first reference voltage signal V
Ref1The time, comparator is exported a high level signal, and the R end through rest-set flip-flop makes control signal D become low level, control signal
Become high level, when the clock signal clk that produces until said clock generating circuit became high level, the S end through rest-set flip-flop made control signal D become high level, control signal
Become low level, realize control switching tube switch motion in the main circuit with this.
Embodiment three
The first reference voltage signal V among the embodiment shown in Figure 5
Ref1Be a preset reference voltage signal, also can adopt embodiment illustrated in fig. 7 in structure: the reference voltage signal V that said output voltage feedback signal FB and presets
Ref2Error amplification signal relatively is again through capacitor C
2Compensation after the reference voltage signal V that obtains
C-refAs said first reference voltage signal.
Embodiment four
The compensation control circuit of DC converter provided by the present invention; Can be applied to decide in the DC converter of frequency pattern; Also can be applied in the DC converter of variable mode; In Fig. 5 and the said embodiment of Fig. 7, the clock signal control system of deciding frequency that clock generating circuit produces is operated in decides the frequency pattern, below is applied in the situation of the DC converter of variable mode with Fig. 8 and the present invention of explanation embodiment illustrated in fig. 9; Its operation principle and embodiment illustrated in fig. 5 similar repeats no more at this.
With reference to figure 8, be depicted as the structural representation that is operated in an embodiment of variable mode according to the compensation control circuit of DC converter of the present invention; Wherein, the comparator that said first control unit comprises, its inverting input receive the signal after said output voltage feedback signal FB, sample rate current signal and the ramp signal addition, and in-phase input end receives the said first reference voltage signal V
Ref1, its output is exported the comparison signal of the two as said first control signal.
Said second control unit comprises a constant ON time control circuit, and its output signal is controlled said step-down type dc converter and is operated in variable mode as said second control signal.
Said switching signal generation circuit comprises a rest-set flip-flop, and its S termination is received said first control signal, and the R termination is received said second control signal, and Q end and Q end be output switch control signal D and D respectively, with the action of the switching tube in the control main circuit.
Embodiment five
With reference to figure 9, be depicted as the structural representation that is operated in another embodiment of variable mode according to the compensation control circuit of DC converter of the present invention; Wherein, the comparator that said first control unit comprises, its in-phase input end receive the signal after said output voltage feedback signal FB, sample rate current signal and the ramp signal addition, and inverting input receives the said first reference voltage signal V
Ref1, its output is exported the comparison signal of the two as said first control signal.
Said second control unit comprises a constant turn-off time control circuit, and its output signal is controlled said step-down type dc converter and is operated in variable mode as said second control signal.
Said switching signal generation circuit comprises a rest-set flip-flop; Its R termination is received said first control signal; The S termination is received said second control signal, and Q end and Q end difference output switch control signal D and
are with the action of the switching tube in the control main circuit.
Be that to be example be described the compensation control circuit of DC converter the step-down type dc converter with the topological structure of main circuit among the above embodiment; But it doesn't matter for the topological structure of the compensation control circuit of DC converter provided by the present invention and DC converter; Therefore; The compensation control circuit of this DC converter can be applicable in the DC converter of any proper topologies structure equally, and preferred topological structure is step-down type dc converter, booster type DC converter, buck-boost type DC converter and inverse-excitation type DC converter etc.
Embodiment six
Describe the compensation control circuit of DC converter provided by the present invention above in detail, introduce the compensating control method of DC converter provided by the present invention below.
With reference to Figure 10, be the compensating control method schematic flow sheet of a kind of DC converter provided by the present invention, this method specifically comprises the steps:
Step S1: obtain an output voltage feedback signal after the output voltage of main circuit handled.
Step S2: the inductive current in the main circuit is sampled, to obtain the sample rate current signal.
The practical implementation process can comprise in this step: in each switch periods inductive current ascent stage in the main circuit or the set time section in the decline stage are carried out analog sampling or its set time point is carried out digital sample, to obtain said sample rate current signal.
Step S3: produce a ramp signal.
Step S4: with said output voltage feedback signal, sample rate current signal and ramp signal addition, and the signal and first reference voltage signal after the addition are compared, export first control signal.
Step S5: export second control signal, control said DC converter and be operated in variable mode or fixed pattern frequently.
Step S6: according to said first control signal and second control signal, the switch controlling signal of the switching tube in the output main circuit.
In the compensating control method shown in the present embodiment, wherein the topological structure of main circuit is preferably step-down type dc converter, booster type DC converter, buck-boost type DC converter or inverse-excitation type DC converter.
The compensating control method of DC converter provided by the present invention only need rationally be provided with the slope of sampling coefficient and ramp signal, can make whole system under steady-working state, obtain rational stable state allowance and Fast Dynamic responds.Simpler relatively in this specification to the description of method part, but the description of relevant similarity reference circuit part.
To the above-mentioned explanation of the disclosed embodiments, make this area professional and technical personnel can realize or use the present invention.Multiple modification to these embodiment will be conspicuous concerning those skilled in the art, and defined General Principle can realize under the situation that does not break away from the spirit or scope of the present invention in other embodiments among this paper.Therefore, the present invention will can not be restricted to embodiment illustrated herein, but will meet and principle disclosed herein and features of novelty the wideest corresponding to scope.