CN108696125B - Buck-Boost converter control method with duty ratio bias - Google Patents
Buck-Boost converter control method with duty ratio bias Download PDFInfo
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- CN108696125B CN108696125B CN201810589287.4A CN201810589287A CN108696125B CN 108696125 B CN108696125 B CN 108696125B CN 201810589287 A CN201810589287 A CN 201810589287A CN 108696125 B CN108696125 B CN 108696125B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
- H02M3/1582—Buck-boost converters
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Abstract
A Buck-Boost converter control method with duty ratio bias belongs to the technical field of power electronics. The method is used for a double-tube Buck-Boost converter, the same offset c is respectively added and subtracted in a duty ratio control signal d output by a controller, and the obtained actual duty ratio signal d is used1D + c for driving Buck tubes, d2D-c is used for driving Boost tube and is used for modulating d1And d2The phase of the carrier signal is staggered by 180 degrees, so that the single-mode operation of the Buck-Boost converter and the balance of high-frequency ripples and average current of inductive current of the Buck-Boost converter can be realized. The invention provides a method for setting duty ratio bias c in a specific input voltage variation range, which ensures that double tubes of a Buck-Boost converter can work in a linear regulation range without saturation of the duty ratio and can ensure that the Buck-Boost converter has good control performance in an operation range.
Description
Technical Field
The invention belongs to the technical field of power electronics, and particularly relates to a control method of a Buck-Boost converter with duty ratio bias.
Background
The double-tube Buck-Boost converter has the input and output voltage homopolarity and the Buck-Boost characteristic, and is suitable for the preceding stage direct current conversion of a two-stage converter with wide input voltage. From the control mode, there are two main types: one mode is a dual-mode working mode, namely, according to the magnitude of input direct-current voltage, the Buck-Boost converter can respectively operate in a Buck mode (a voltage reduction mode) and a Boost mode (a voltage boosting mode), and the problem of how to realize smooth switching exists between the Buck mode and the Boost mode; the other working mode is a single-mode working mode, namely, a Buck-Boost converter with double tubes is subjected to unified modeling, and is controlled by adopting a unified duty ratio (driving signals of the two tubes can be synchronous and can have a certain phase difference). However, this operation mode has a problem that the inductor current ripple is relatively large or the average value of the inductor current is high. The control strategy provided by the invention can improve the existing problems to a certain extent.
Disclosure of Invention
The invention aims to provide a control method of a Buck-Boost converter with duty ratio bias. A Buck-Boost converter control method with duty ratio bias and a duty ratio bias setting method for ensuring that double tubes of the Buck-Boost converter can work in a linear regulation range without duty ratio saturation are provided.
The purpose of the invention is realized as follows:
the voltage of a main circuit front-end direct-current power supply of a Buck-Boost converter with duty ratio bias is vinThe output current of the DC power supply is iinA capacitor C connected in parallel at both ends of the DC power supply1For stabilizing the output of the dc power supply. Capacitor C1One end connected with the positive pole of the direct current power supply is connected with a switch tube S1Called Buck tube, the other end of which is connected with a diode D1I.e. point a as marked in figure 1. D1The other end of the second switch is connected with the negative electrode of the direct current power supply. The point A is connected to one end of an inductor L, and the other end of the inductor L, i.e. the point B marked on the attached figure 1, is connected to a switch tube S2The other end of the Boost tube is connected with the negative electrode of the direct current power supply. Point B is connected with a diode D2Anode of (D)2Cathode of (2) is connected with a capacitor C2One end of (A), C2The other end of the second switch is connected with the negative electrode of the direct current power supply. Capacitor C2Namely the output filter capacitor of the Buck-Boost converter.
A control method of a Buck-Boost converter with duty ratio bias comprises the following steps:
(1) and determining the duty ratio bias signal c according to the change range of the input side direct current power supply voltage and the expected output voltage value.
(2) Two columns of sawtooth carriers CW1 and CW2 are generated in the control system, with a phase difference of 180 ° from each other. Wherein, the sawtooth carriers CW1 and CW2 are different from each other by 180 DEG to form a pair S1And S2To reduce high frequency ripple of the inductor current.
(3) Calculating voltage control deviation according to the output voltage detected by the voltage sensor, and sending the calculated voltage control deviation to the voltage controller GvPerforming calculation to obtain controlThe signal d.
(4) Applying a positive bias c to the control signal d to obtain d1D + c. Applying a negative bias c to the control signal d to obtain d2D-c. Applying a positive bias c to d to obtain d1D + c and for S1The tube is controlled to raise the diode D as much as possible1The average value of the terminal voltages (the voltage is the input voltage of the equivalent Boost converter marked by the dashed frame at the rear end). Under the condition of the same load power, the higher the voltage is, the smaller the average value of the inductance current is.
(5) D is respectively paired by two rows of sawtooth carriers CW1 and CW2 with the phase difference of 180 DEG1And d2Modulating to obtain respectively-driven switch tubes S1And S2The pulse signal of (2).
(6) If the expected control effect is not achieved, the corresponding design steps in (1) - (5) are returned until a satisfactory actual result is obtained.
The process of determining the duty ratio offset signal c in the step (1) of the control method of the Buck-Boost converter with the duty ratio offset is as follows:
current i of inductor L in main circuit of Buck-Boost converterLIn the continuous case have
Wherein d is1Is S1Duty ratio of the tube, d2Is S2Duty cycle of the tube.
Defining:
wherein d is a signal output by the controller, and c is a duty ratio bias signal required to be determined.
According to formula (2) having
d1-d2＝2c＝c2(3)
From (1) and (2) can be obtained
Assuming that the duty cycle of the switching tube needs to be limited in practical application, the following is shown:
then according to (4) and (5) can be obtained
Again according to the input voltage vinCan be varied within a range
Wherein v isinmaxAnd vinminAre each vinMaximum and minimum values of.
By combining (6) and (7), can be obtained
To this end, according to (8), the range of the duty ratio offset signal c can be determined as
The invention has the beneficial effects that:
(1) the same offset c is respectively added and subtracted in a duty ratio control signal d output by a Buck-Boost converter controller, the obtained actual duty ratio signal d1 which is d + c is used for driving a Buck tube, d2 which is d-c is used for driving a Boost tube, and the duty ratio signals d1 and d2 are staggered in phase by 180 degrees. Therefore, single-mode operation of the Buck-Boost converter and balance of high-frequency ripples and average current of inductive current of the Buck-Boost converter can be realized;
(2) the invention provides a method for setting duty ratio bias c in a specific input voltage variation range, which can ensure that double tubes of a Buck-Boost converter can work in a linear regulation range without saturation of the duty ratio, and can ensure that the Buck-Boost converter has good control performance in an operation range because possible saturation of a switching tube in the Buck-Boost converter is avoided.
Drawings
Fig. 1 is a flowchart illustrating an implementation of a Buck-Boost converter control method with duty cycle offset;
FIG. 2 is a schematic diagram of a main circuit of a Buck-Boost converter with duty cycle bias;
fig. 3 is a schematic diagram of a control method of duty ratios of two switching tubes of a Buck-Boost converter with duty ratio bias.
Detailed Description
The following further describes embodiments of the present invention with reference to the accompanying drawings:
the invention provides a control strategy and a design method for realizing single-mode operation of a Buck-Boost converter by applying duty ratio bias and realizing balance of high-frequency ripple and average current of inductive current of the Buck-Boost converter. The method is used for a double-tube Buck-Boost converter, the same offset (c) is added to and subtracted from a duty ratio control signal (d) output by a controller respectively, and the obtained actual duty ratio signal (d) is used1D + c) for driving Buck tubes, (d) will be2D-c) is used for driving the Boost tube. And will be used to modulate d1And d2Are 180 deg. out of phase. The patent provides a design method of duty ratio bias c in a specific input voltage variation range, so that the double tubes of the Buck-Boost converter can work in a linear regulation range without saturation of the duty ratio.
A Buck-Boost converter control strategy with duty ratio bias and a design method are as follows:
(1) by adding and subtracting the same offset (c) to and from the duty cycle control signal (d) output by the Buck-Boost converter controller, respectively, and applying the actual duty cycle signal (d) obtained1D + c) for driving Buck tubes, (d) will be2D-c) is used for driving the Boost tube. And duty ratio signal d1And d2With a 180 phase shift. In this way, single-mode operation of the Buck-Boost converter can be realized, and the inductance current of the Buck-Boost converter is balanced with high-frequency ripple and average current.
(2) The design method of the duty ratio bias c in a specific input voltage variation range can ensure that double tubes of the Buck-Boost converter can work in a linear regulation range without saturation of the duty ratio, and can ensure the control performance of the Buck-Boost converter in an operation range due to the fact that saturation possibly occurring in a switching tube in the Buck-Boost converter is avoided.
Fig. 1 shows a main circuit of a Buck-Boost converter as described in the patent. The voltage of the front end DC power supply is vinThe output current of the DC power supply is iinA capacitor C connected in parallel at both ends of the DC power supply1For stabilizing the output of the dc power supply. Capacitor C1One end connected with the positive pole of the direct current power supply is connected with a switch tube S1Called Buck tube, the other end of which is connected with a diode D1Such as indicated by point a in figure 1. D1The other end of the second switch is connected with the negative electrode of the direct current power supply. The point A is connected to one end of an inductor L, and the other end of the inductor L, i.e. the point B in FIG. 1, is connected to a switching tube S2The other end of the Boost tube is connected with the negative electrode of the direct current power supply. Point B is connected with a diode D2Anode of (D)2Cathode of (2) is connected with a capacitor C2One end of (A), C2The other end of the second switch is connected with the negative electrode of the direct current power supply. Capacitor C2Namely the output filter capacitor of the Buck-Boost converter.
Fig. 2 shows a duty ratio control strategy (taking voltage single closed-loop control as an example) of a double-tube of the Buck-Boost converter disclosed in the patent. The difference between the output voltage command vo and the actual voltage vo detected by the voltage sensor VS is fed to the voltage regulator Gv to be calculated to obtain a control signal d, and one offset signal c is added to d to obtain a duty ratio control signal d1 ═ d + c; meanwhile, subtracting an offset signal c from d to obtain a duty ratio control signal d2 ═ d-c; d1 and d2 are modulated by two columns of high frequency sawtooth carriers 180 DEG out of phase with each other (CW1 and CW2 180 DEG out of phase). The pulse signal obtained by modulating d1 is used to drive the S1 tube, and the pulse signal obtained by modulating d2 is used to drive the S2 tube.
Claims (4)
1. A method of controlling a Buck-Boost converter with duty cycle bias, comprising:
(1.1) according to the input voltage v of the direct current power supply at the input side of the front end of the main circuit of the Buck-Boost converterinRange of variation and desired output voltage value voDetermining a duty ratio bias signal c; the range of the duty ratio bias signal c is as follows:
wherein d isminIs the minimum value of the duty ratio of the switching tube; dmaxThe maximum value of the duty ratio of the switching tube is obtained; v. ofinmaxIs v isinMaximum value of (d); v. ofinminIs v isinMinimum value of (d);
(1.2) generating two columns of a first saw-tooth carrier CW1 and a second saw-tooth carrier CW2 which are 180 ° out of phase with each other in a control system;
(1.3) calculating the difference between the output voltage and the actual voltage to be the voltage control deviation according to the output voltage detected by the voltage sensor, and sending the voltage control deviation to the voltage controller GvCalculating to obtain a control signal d;
(1.4) applying a positive bias c to the control signal d to obtain d1D + c; applying a negative bias c to the control signal d to obtain d2＝d-c；
(1.5) using a first sawtooth carrier CW1 for d1Modulating to obtain a driving switch tube S1The pulse signal of (3); using a second sawtooth carrier CW2 for d2Modulating to obtain a driving switch tube S2The pulse signal of (3);
(1.6) if the expected control effect is not achieved, returning to the corresponding steps of (1.1) - (1.5) until the expected control effect is achieved; the expected control effect is that the double tubes of the Buck-Boost converter can work in a linear regulation range without saturation of the duty ratio.
2. The Buck-Boost converter control method with duty cycle bias according to claim 1, wherein: two ends of a direct current power supply at the input side of the front end of the main circuit of the Buck-Boost converter are connected with a capacitor C in parallel1Capacitor C1One end connected with the positive pole of the direct current power supply is connected with a switch tube S1Switching tube S1Called Buck tube, the other end of the Buck tube is connected with the cathode of a diode D1 at point A1The other end of the inductor is connected with the negative pole of a direct current power supply, the point A is connected with one end of an inductor L, the point B at the other end of the inductor L is connected with a switch tube S2Switching tube S2The other end of the Boost tube is connected with the cathode of a direct current power supply, and a point B is connected with a diode D2Anode of (D)2Cathode of (2) is connected with a capacitor C2One end of (A), C2The other end of the second switch is connected with the negative electrode of the direct current power supply.
3. The Buck-Boost converter control method with duty cycle bias according to claim 1, wherein: the duty cycle offset signal c is determined as follows,
current i of inductor L in main circuit of Buck-Boost converterLIn the continuous case have
Wherein d is1Is a switch tube S1Duty ratio of d2Is a switch tube S2Duty cycle of (d); c. C1At a desired output voltage value voAnd an input voltage vinThe ratio of (A) to (B);
defining:
wherein d is a control signal output by the controller, and c is a duty ratio bias signal required to be determined;
according to (3.2) have
d1-d2＝2c＝c2(3.3)
c2Is 2 times of the duty ratio bias signal required to be determined;
from (3.1) and (3.2)
In practical application, the duty ratio of the switching tube needs to be limited, as follows:
wherein d ismin+dmax＝1，dminIs the minimum value of the duty cycle of the switching tube, dmaxThe maximum value of the duty ratio of the switching tube is obtained;
then according to (3.4) and (3.5) can be obtained
According to input voltage vinCan be varied within a range
Wherein v isinmaxIs v isinMaximum value of vinminIs v isinMinimum value of (d);
the combination of (3.6) and (3.7) can give
To this end, the duty ratio offset signal c can be determined in the range of (3.8)
4. The Buck-Boost converter control method with duty cycle bias according to claim 1, wherein: the sawtooth carriers CW1 and CW2 with the phase difference of 180 DEG form a pair of switching tubes S1And a switching tube S2The high-frequency ripple of the inductive current can be reduced by the staggered modulation.
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| CN109494985B (en) * | 2018-11-30 | 2020-12-29 | 电子科技大学 | Full-duty-ratio current-sharing control method based on interleaved Boost converters in parallel |
| CN110045170B (en) * | 2019-04-01 | 2021-06-22 | 漳州科华技术有限责任公司 | Method, system and device for detecting inductive current of step-up/step-down circuit |
| CN110429847B (en) * | 2019-08-19 | 2021-05-04 | 西安爱科赛博电气股份有限公司 | Method and circuit for generating driving signals of switching tubes of double Buck inverters |
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