CN113489323B - Online real-time efficiency optimization control method and device for four-switch buck-boost converter - Google Patents

Online real-time efficiency optimization control method and device for four-switch buck-boost converter Download PDF

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CN113489323B
CN113489323B CN202110670238.5A CN202110670238A CN113489323B CN 113489323 B CN113489323 B CN 113489323B CN 202110670238 A CN202110670238 A CN 202110670238A CN 113489323 B CN113489323 B CN 113489323B
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CN113489323A (en
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刘华吾
王廷营
王亚洲
赵瑞
王永生
崔满超
唐海瑞
曹赟
丁星星
戚宏伟
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Lianyungang Jierui Electronics Co Ltd
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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
    • 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
    • H02M3/157—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 with digital control

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  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention discloses an online real-time efficiency optimization control method of a four-switch buck-boost converter, which comprises the following steps: when the four-switch lifting converter is in a stable state, the ratio of the time values of the input stage and the input-output stage of the converter is adjusted on line in real time, so that the ratio of the time values of the input-output stage in the whole switching period is maximized, and if the ratio of the time values of the input-output stage is larger, the output voltage has a change trend of falling. The invention can maximize the ratio of the input and output high-efficiency transmission stages of the converter in the whole switching period by adjusting the ratio of the input stage and the input-output stage of the converter in real time on line, so that the converter can achieve higher conversion efficiency under various different working conditions. The invention has simple and convenient control logic, is not influenced by the hardware parameter deviation of the converter, and can carry out efficiency optimization in real time.

Description

Online real-time efficiency optimization control method and device for four-switch buck-boost converter
Technical Field
The invention relates to the technical field of converters, in particular to an online real-time efficiency optimization control method and device for a four-switch buck-boost converter.
Background
The four-switch Buck-Boost (Buck-Boost) converter is a DC/DC circuit topology, and is widely applied to the power supply fields of aerospace, communication, military weapons and the like due to the characteristics of high efficiency, reliability, flexibility, wide input and output range and the like. The four-switch Buck-Boost converter shown in fig. 1 includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, and an inductor L. One end of the inductor L is connected between the first switch S1 and the second switch S2, and the other end of the inductor L is connected between the third switch S3 and the fourth switch S4; fig. 1 further includes an inverter controller for controlling the on and off of the first switch S1 through the fourth switch S4. Input source with voltage VinInputting power to the converter, passing through the converter, the power being output at an output voltage VoTo the output load.
Briefly, the four-switch Buck-Boost converter is divided into four stages in one switching cycle, as shown in fig. 2; namely an input stage, an input-output stage, a freewheeling stage and a clamping stage. In the input phase, the first switch S1 and the fourth switch S4 are turned on, and the input voltage and the ground are applied across the inductor L, respectively, and in this phase the inductor current flows
Figure GDA0003553946920000011
The slope of (a) rises, and the inductor L starts to store energy at this stage; a second stage, an input-output stage; in this stage, the first switch S1 and the third switch S3 are turned on, the input voltage and the output voltage are applied to the two ends of the inductor L, and the inductor current flows
Figure GDA0003553946920000012
The input end and the converter inductor transmit energy to the load together at the stage; the third stage, follow current stage; the second switch S2 and the third switch S3 are turned on; an output voltage and a ground terminal are respectively applied to two ends of an inductor L, and the inductor current is equal to
Figure GDA0003553946920000013
The slope of the inductor is reduced, and the energy in the inductor L is transferred to a load end; clamping stage ofThe two switches S2 and the fourth switch S4 are turned on, the inductor current remains unchanged, and the converter neither absorbs energy from the input nor outputs energy to the load.
The converter controller in fig. 1 controls the on and off of the first switch S1 to the fourth switch S4 to control the cycle ratio of each stage, so as to ensure that the converter outputs stable output voltage under the working conditions of different voltage inputs, different loads, and the like. As can be seen from fig. 2, the buck-boost converter has an input stage T in one switching cycle1Input-output phase T2In the follow current stage T3Clamping stage T4When the converter is controlled, at least 3 variables can be controlled and adjusted, that is, the converter can have multiple stable states under the condition of the same input voltage and the same output load, fig. 3A and 3B show two possible stable states of the inductive current under the same load under the working condition of the same input voltage and the same output voltage, and it can be seen from the graphs that the effective values of the inductive current have obvious differences, that is, the efficiency of the converter has obvious differences.
In fact, in order to improve the efficiency of the four-switch buck-boost converter, it is necessary to optimize a control method, select reasonable control variables, and reasonably allocate the time ratios of an input stage, an input-output stage, a freewheeling stage, and a clamping stage, and numerous patents and documents have been studied. In patent CN 106849659, different circuit control strategies are set in three different working modes, namely buck, Boost and buck-Boost, respectively, to improve power conversion efficiency, which is complicated and tedious, and when a working mode changes, the control strategy needs to be changed to maximize efficiency. However, this approach is complicated in control circuitry and requires resistive current sampling, which is a high requirement for hardware circuitry and losses due to resistive sampling further affect converter efficiency. In a document a Constant Frequency ZVS Control System for the Four-Switch Buck-Boost DC-DC Converter With Reduced indicator Current, time allocation under various working conditions is calculated off-line, and a method of lookup tables and linear interpolation is used to Control the Converter to output stably.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides an online real-time efficiency optimization control method and device for a four-switch buck-boost converter, which can maximize the ratio of an input-output high-efficiency transmission stage of the converter in the whole switching period by adjusting the proportion of the input stage and the input-output stage of the converter in real time online, so that the converter can achieve higher conversion efficiency under various different working conditions. The invention has simple and convenient control logic, is not influenced by the hardware parameter deviation of the converter, and can carry out efficiency optimization in real time.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, an embodiment of the present invention provides an online real-time efficiency optimization control method for a four-switch buck-boost converter, where one switching cycle of the four-switch buck-boost converter is sequentially divided into four stages: an input stage, an input-output stage, a follow current stage and a clamping stage; in the input stage, an input voltage and a ground end are respectively applied to two ends of an inductor, in the input-output stage, the input voltage and an output voltage are respectively applied to two ends of the inductor, in the follow current stage, the output voltage and the ground end are respectively applied to two ends of the inductor, and in the clamping stage, the inductor current is kept unchanged; the control method comprises the following steps:
when the four-switch lifting converter is in a stable state, the time value T of the input-output stage is enabled by adjusting the time value ratio M of the input stage and the input-output stage of the converter in real time on line2The ratio is maximized during the entire switching cycle and if the time value T of the input-output phase is exceeded2The duty ratio is larger, and the output voltage has a falling change trend;
wherein, a phase time value T is input1And the input voltage sampling value VinOutput voltage sampling value VoAnd its maximum value determines the maximum output power of the four-switch buck-boost converter.
Optionally, the control method further includes:
s1, sampling value V of output voltageoAnd an output voltage reference value VorefPerforming subtraction operation, and performing proportional integral operation on the error value between the two values to obtain an output voltage closed-loop regulation value Ver，Ver＝(Kp+Ki/s)×(Voref-Vo) In the formula, KpAnd KiThe constants are respectively proportional and integral coefficients and are related to the specific working conditions of the four-switch buck-boost converter;
s2, sampling value V according to input voltageinOutput voltage sampling value VoClosed loop regulating value V of output voltageerAnd a clamp phase time value T4By clamping the stage time value T4Less than or equal to preset time length threshold upper limit T4THOr a closed-loop regulation value V of the output voltageerReaches the preset upper limit V of the output thresholderTHCalculating to obtain a time value ratio M for an optimization target;
s3, adjusting the duration T of the input-output stage by the time value ratio M in the form of product or addition2。
Optionally, in step S2, the clamping stage is continued for a time period T4Less than a preset upper limit T of the time length threshold4THIn order to optimize the objective, the process of calculating the time value ratio M comprises the following steps:
s201, judging the clamping stage time value T of the four-switch buck-boost converter4Whether the time length exceeds the set upper limit T of the time length threshold4THIf yes, go to step S202, otherwise, go to step S204;
s202, increasing the time value ratio M by the first step length to increase the time value T of the input-output stage2And the converter reaches a new steady state;
s203, reacquiring the sampling value V of the input voltageinOutput voltage sampling value VoAnd a clamp phase time value T4Judging the output voltage sampling value V of the current four-switch converteroWhether or not to reduce or the value V of the sample of the input voltage of the converterinIf the change occurs, resetting the upper limit T of the time length threshold value4THReturning to the step S201, otherwise, directly returning to the step S201;
s204, reducing the time value ratio M by a second step length to reduce the time value T of the input-output stage2And the converter reaches a new steady state, and the process returns to step S201.
Optionally, the upper limit T of the duration threshold is4THThe value range of (1) is [ 5%. times.T ]s,10％×Ts]，TsIs the switching cycle duration.
Optionally, in step S2, the closed-loop regulation value V is outputtederReaches the preset upper limit V of the output thresholderTHIn order to optimize the objective, the process of calculating the time value ratio M includes the following steps:
s211, setting an upper limit V of an output thresholderTH；
S212, judging the closed loop regulating value V of the output voltageerWhether the set threshold value V is reachederTHIf not, go to step S213, otherwise go to step S215;
s213, increasing the time value ratio M by the first step length to increase the time value T of the input-output stage2And the converter reaches a new steady state;
s214, the sampling value V of the input voltage is obtained againinOutput voltage sampling value VoAnd an output voltage closed loop regulation value VerJudging the current output voltage value V of the four-switch converteroWhether to reduce or the input voltage V of the converterinIf so, returning to step S211, otherwise returning to step S212;
s215, reducing the time value ratio M by a second step length to reduce the time value T of the input-output stage2And the converter reaches a new steady state, and returns to step S212.
Optionally, in step S211, the upper limit V of the output threshold is set according to the following formulaerTH：
Figure GDA0003553946920000031
Optionally, in step S3, the duration T of the input-output stage is adjusted by the time value ratio M in the form of a product2Comprises the following steps:
Figure GDA0003553946920000032
Figure GDA0003553946920000033
Figure GDA0003553946920000034
T4＝Ts-T1-T2-T3
in the formula, T1Is an input phase time value, T2Is the input-output phase time value, T3Is the value of the freewheel phase time, T4Is the value of the clamping phase time, TsIs a switching cycle value.
Optionally, in step S3, the duration T of the input-output stage is adjusted by the time value ratio M in an addition manner2Comprises the following steps:
Figure GDA0003553946920000035
in a second aspect, an embodiment of the present invention provides an online real-time efficiency optimization control device for a four-switch buck-boost converter, where the control device includes:
a subtractor for sampling value V of output voltageoAnd an output voltage reference value VorefCarrying out subtraction operation;
an output voltage closed loop regulation module, the input end of which is connected with the output end of the subtracter and used for sampling a value V of an output voltage samplingoAnd an output voltage reference value VorefThe error value between the two is subjected to proportional integral operation to obtain an output voltage closed loop regulating value Ver，Ver＝(Kp+Ki/s)×(Voref-Vo) In the formula, KpAnd KiThe constants are respectively proportional and integral coefficients and are related to the specific working conditions of the four-switch buck-boost converter;
the online efficiency implementation optimization module comprises four input ends which are respectively connected with the output end of the output voltage closed-loop regulation module, the input voltage sampling end, the output voltage sampling end and the T1～T4The clamping stage time value output end of the time period parameter calculation module is connected and used for sampling a value V according to the input voltageinOutput voltage sampling value VoClosed loop regulating value V of output voltageerAnd a clamp phase time value T4By clamping the stage time value T4Less than or equal to preset time length threshold upper limit T4THOr a closed-loop regulation value V of the output voltageerReaches the preset upper limit V of the output thresholderTHCalculating to obtain a time value ratio M for an optimization target;
T1～T4time period parameter calculation Module, T1～T4Three input ends of the time period parameter calculation module are respectively connected with an input voltage sampling end, an output end of the output voltage closed-loop regulation module and an output end of the online efficiency implementation optimization module, and T1～T4The time period parameter calculation module is used for calculating a time period parameter according to the input voltage sampling value VinClosed loop regulating value V of output voltageerCalculating the sum time value proportion M to obtain the time value T of the input stage1Time value T of input-output stage2Time value T of follow current stage3And a clamp phase time value T4Wherein, T1～T4The time period parameter calculation module adjusts the duration T of the input-output stage in a multiplication or addition mode by the time value proportion M2；
A PWM generation module for generating a PWM signal according to T1～T4Input stage time value T output by time period parameter calculation module1Time value T of input-output stage2Time value T of follow current stage3And a clamp phase time value T4And generating on-off control signals of four switches of the corresponding converter.
The beneficial effects of the invention are:
the invention can maximize the ratio of the input and output high-efficiency transmission stages of the converter in the whole switching period by adjusting the ratio of the input stage and the input-output stage of the converter in real time on line, so that the converter can achieve higher conversion efficiency under various different working conditions. The invention has simple and convenient control logic, is not influenced by the hardware parameter deviation of the converter, and can carry out efficiency optimization in real time.
Drawings
Fig. 1 is a power circuit of a four-switch Buck-Boost converter.
Fig. 2 is a sequence of switching cycles of a four-switch Buck-Boost converter.
Fig. 3 is a waveform diagram of current flowing through the inductor L in two different time distribution manners, fig. 3A is a waveform diagram of current flowing through the inductor L in a first time distribution manner, and fig. 3B is a waveform diagram of current flowing through the inductor L in a second time distribution manner.
Fig. 4 is a schematic diagram of an online real-time efficiency optimization control circuit structure of the four-switch buck-boost converter of the present invention.
FIG. 5 is a schematic diagram of one embodiment of an online efficiency real-time optimization module.
FIG. 6 is a schematic diagram of another embodiment of an online efficiency real-time optimization module.
Fig. 7 is a schematic diagram showing comparison results of waveforms of the four-switch buck-boost converter according to the embodiment of the present invention and the four-switch buck-boost converter according to the conventional technology, where fig. 7A is a waveform diagram of the four-switch buck-boost converter according to the embodiment of the present invention, and fig. 7B is a waveform diagram of the four-switch buck-boost converter according to the prior art.
Fig. 8 is a graph comparing power efficiency of an embodiment of the present invention with control power efficiency of a conventional art.
Fig. 9 is a flowchart of an online real-time efficiency optimization control method for a four-switch buck-boost converter according to an embodiment of the present invention.
Detailed Description
The present invention will now be described in further detail with reference to the accompanying drawings.
It should be noted that the terms "upper", "lower", "left", "right", "front", "back", etc. used in the present invention are for clarity of description only, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not limited by the technical contents of the essential changes.
Fig. 9 is a flowchart of an online real-time efficiency optimization control method for a four-switch buck-boost converter according to an embodiment of the present invention. The embodiment is applicable to the case of performing optimal control on the real-time efficiency of the four-switch lifting converter, and the method can be performed by an online real-time efficiency optimal control device of the four-switch lifting converter as shown in fig. 4.
The online real-time efficiency optimization control device of the embodiment can be directly applied to a four-switch lifting converter in the prior art. For convenience of description, the present embodiment is still illustrated with a conventional four-switch buck-boost converter as a control object. In the present embodiment, the four-switch buck-boost converter main power circuit 400 includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, and an inductor L. One end of the inductor L is connected between the first switch S1 and the second switch S2, and the other end of the inductor L is connected between the third switch S3 and the fourth switch S4; input source with voltage VinInputting power to the converter, passing through the converter, the power being output at an output voltage VoTo the output load. On-off control of the first switch S1 to the fourth switch S4 is controlled by an online real-time efficiency optimization control device (converter controller) 401, and optionally, the converter controller 401 may be a Digital Signal Processor (DSP), a micro-processor MCU, or a field programmable logic device FPGA.
Referring to fig. 4, from the overall perspective of the converter controller 401, the converter controller 401 includes a first input signal terminal (for receiving the sampled input voltage V of the main power circuit 400)in) And a second input signal terminal(for receiving the output voltage sample value V of the main power circuit 400)o) And four signal output terminals for outputting on-off control signals TS1, TS2, TS3, TS4 for controlling the first to fourth switches S1 to S4 of the main power circuit 400. In the circuit, the online real-time efficiency optimization control device 401 of the four-switch buck-boost converter further comprises a subtractor 402, an output voltage closed-loop regulation module 403, an online efficiency implementation optimization module 406, a time period parameter calculation module 404 from T1 to T4 and a PWM generation module 405.
(one) subtractor 402
A subtractor 402 for performing the output voltage sample value VoAnd an output voltage reference value VorefThe output signal of the subtractor 402 serves as the input signal of the output voltage closed-loop adjustment module 403.
(II) output voltage closed-loop regulation module 403
Output voltage closed loop regulation module 403 for output voltage VoAnd outputting the reference value VorefIs subjected to proportional integral operation, i.e. Ver＝(Kp+Ki/s)×(Voref-Vo) (ii) a Wherein K ispAnd KiThe specific values can be optimally designed according to the specific working conditions of the four-switch buck-boost converter.
(III) T1～T4Time period parameter calculation module 404
T1～T4Time period definition referring to fig. 2, the time period is an input stage, an input-output stage, a freewheeling stage and a clamping stage, and the corresponding time values are T1、T2、T3And T4。T1～T4The input signal terminal of the time period parameter calculation module 404 includes the input voltage sample value V of the four-switch buck-boost converterinOutput voltage sampling value VoOutput value V of the output voltage closed loop regulation module 403erAnd the real-time optimized output value M of the online efficiency enforcement optimization module 406. T is1～T4The parameter calculation result of the time period parameter calculation module 404 determines four stages of the four-switch buck-boost converterThe ratio distribution in one switching period further determines the conversion efficiency of the converter. T is1～T4The key input signal on which the time period parameter calculation module 404 optimizes the efficiency of the four-switch buck-boost converter is the output value M of the online efficiency real-time optimization module of the online efficiency implementation optimization module 406.
T1～T4The time period parameter calculation module 404 calculates T1～T4The specific calculation formula of the time period parameter has various forms, and one of the feasible modes of the embodiment of the invention is as follows:
Figure GDA0003553946920000061
Figure GDA0003553946920000062
Figure GDA0003553946920000063
T4＝Ts-T1-T2-T3 (4)
in formulae (1) to (4), VerIs the output value of the output voltage closed loop adjustment module 403; m is the output value of the online efficiency implementation optimization module 406; t issIs the time value of the switching cycle of the four-switch buck-boost converter 400. T in formula (1)1Calculated value of (d) and input voltage VinIn inverse proportion, the dynamic response of the converter is improved; t is1Is simultaneously compared with the output value V of the output voltage closed-loop regulation module 403erIs in direct proportion to realize the output voltage stabilizing control of the four-switch buck-boost converter. When the output voltage V isoIncrease T when falling1Time, conversely, at the output voltage VoAt the time of rising, T is decreased1Time. T in formula (2)2Calculated value of time period and input voltage VinAnd an output voltage VoThe difference between them is in inverse proportion and is simultaneously closed with the output voltageThe output value V of the regulation module 403erIs in direct proportion to the output value M of the on-line real-time efficiency optimization module. T is3Is given a value of T1、T2And the input-output voltage of the converter, T3The corresponding freewheeling stage is used to ensure reliable resetting of the inductor current. T is4By switching period T of the buck-boost convertersMinus T1、T2、T3The time remaining after the time period. Note that, for convenience of calculation, in the present embodiment, T is set to be T1、T2、T3、T4And TsAre set to be dimensionless parameters. In other cases, it can also be directly set as the time parameter, and correspondingly, the calculation target of the above formula is modified to the duration of each phase and the switching period TsThe proportional value of (c).
As can be seen from the above equations (1) to (4), the present embodiment adjusts T2And T1By adjusting T in said equation (2), in particular2And T1The scaling factor M to achieve the optimization of the converter efficiency. Taking FIGS. 3A and 3B as examples, T in FIG. 3B2The time period cycle ratio is significantly less than T in FIG. 3A2The time period is proportional to the effective value of the inductor current in fig. 3A, which corresponds to the effective value of the inductor current in fig. 3B under the same operating condition. In general, for a four-switch buck-boost converter, T2The longer the corresponding input-output phase duty cycle, the higher the overall conversion efficiency of the converter. Further, from the analysis of the working mode of the converter in fig. 1, T2In the corresponding input-output stage, namely, the first switch S1 and the third switch S3 are turned on simultaneously, the input voltage is directly connected to the output through the first switch S1, the inductor L and the third switch S3, and the input energy is directly and most efficiently transferred to the output side path. Thus, T2The higher the ratio of the corresponding input-output stage in one switching period is, the more the energy transfer time with high efficiency is, and the higher the overall conversion efficiency of the corresponding buck-boost converter is inevitably. It should be noted that T of buck-boost converter3Duration is subject to T1And T2Time period duration influence, in fact, T3The duration of the corresponding freewheel phase is determined by the magnetic reset time of the inductor L of the buck-boost converter. In the normal case, T2The longer the period ratio of the corresponding input-output stage, the smaller the peak current of the inductor L, T3The smaller the period occupancy of the corresponding freewheel phase. Accordingly, T4The cycle occupancy of the time period also becomes smaller. To summarize, increasing T1～T4The output value M of the real-time optimization module of the time period parameter calculation module 404 increases the cycle ratio time of the input-output stage of the buck-boost converter, and further T3And T4Will decrease, as is evident from a comparison of fig. 3A and 3B. On the other hand, T2The corresponding input-output stage is the stage with the highest input-output power transfer efficiency of the buck-boost converter, and increasing the cycle ratio of the input-output stage means improving the conversion efficiency of the converter.
It should be noted that, in addition to the possible four-switch buck-boost converters T of equations (1) to (4), the four-switch buck-boost converter T may be used1～T4Other possible embodiments include the formula for the time period parameter, including1Making adjustments, e.g. T1Is only compared with the output value V of the output voltage closed-loop regulation module 403erIn direct proportion, e.g. T1＝VerOr T is1＝Tx+Ver. Feasible T2Embodiments of (A) can also be similarly adapted, e.g.
Figure GDA0003553946920000071
And the like. It should be noted that the present embodiment adjusts T2And T1The efficiency of the converter is optimized by the proportion, and the adopted proportion adjusting mode does not depend on the four-switch buck-boost converter T1～T4The specific calculation mode of the time period parameter.
In addition, equation (2) can adjust the time value of the input-output stage in the form of addition, in addition to adjusting the time value of the input-output stage in the form of product by the output value M of the online efficiency real-time optimization module, for example,
Figure GDA0003553946920000072
it should be understood that this is only one of them with respect to T2The calculation method of (1) may be further to obtain T by multiplying M by a certain limiting parameter and then adding the obtained M to the previous part2，T2The value of (a) is more dependent on the operation requirement of the four-switch step-up-and-down transformer.
(IV) Online efficiency implementation optimization Module 406
The efficiency of the four-switch buck-boost converter is optimized in real time on line by optimizing the period ratio time of the input-output phase, and the adjustment basis of the period ratio time of the input-output phase is the on-line efficiency implementation optimization module 406 in fig. 4. The online efficiency implementation optimization module 406 includes four signal inputs: the first signal input is the output voltage closed-loop regulator output value V of the output voltage closed-loop regulation module 403er(ii) a The second signal input is the time value T of the fourth output clamping stage of the parameter calculation module 404 for the time period T1-T44(ii) a The third signal input value is an output voltage sampling value V of the four-switch buck-boost convertero(ii) a The fourth signal input value is an input voltage sampling value V of the four-switch buck-boost converterin. It should be noted that during the actual operation of the converter, the online efficiency optimization mechanism of the time period parameter calculation module 404 from T1 to T4 may be set to be only performed in a steady state, and the adjustment speed of the optimization mechanism is relatively slow, so as to avoid affecting the closed-loop adjustment of the output voltage of the main control loop of the converter.
There are various embodiments of the online efficiency implementation optimization module 406, the core of which is based on the first signal input VerA second signal input quantity T4And the sampling value V of the output voltage of the third input converteroAnd a fourth input value converter input voltage sample value VinAnd identifying the current state of the inductor L of the current four-switch buck-boost converter to determine T2If the time period has a space for continuous adjustment, if T2There is still room for continued increase, then M is increased to increase T2Of a period of timeThe period ratio; if due to T2If the time period is too large and the output voltage drops, M is reduced to reduce T2The period of the time period is proportional.
An embodiment of the online efficiency implementation optimization module 406 will be described with reference to fig. 5 and 6.
FIG. 5 is a schematic diagram of one embodiment of an online efficiency real-time optimization module. The implementation method comprises the following steps:
500, obtaining the output voltage V of the four-switch buck-boost converteroInput voltage VinOutput value V of an output voltage closed-loop regulator of a controller of the converterer(i.e., the output value of the output voltage closed-loop adjustment module 403 of fig. 4).
501, setting an upper limit V of an output threshold of the output voltage closed-loop regulation module 403erTH(ii) a Upper limit of output threshold V seterTHOn the one hand, the time value T of the input-output phase of the maximum allowable four-switch buck-boost converter is identified2On the other hand, the time value T of the maximum permissible input phase is also identified1. Note that T is1Determines the maximum output power of the four-switch buck-boost converter. Upper threshold V of output voltage closed loop regulation module 403erTHThe setting method is flexible, and can be set in a table look-up form or through a specific mathematical expression. When a mathematical expression is adopted, the selected mathematical expression usually needs the first time period T of the four-switch buck-boost converter1To the fourth time period T4Corresponds to, for example, one possible preferred formula is shown in equation (5):
Figure GDA0003553946920000081
502, judging the output value V of the current output voltage regulatorerWhether the set threshold value V is reachederTH. If the output value of the output voltage closed-loop adjustment module 403 does not reach the upper limit of the output threshold VerTHMean that the current four-switch buck-boost converter is not in operationAt an optimum point of efficiency, i.e. time value T2If there is still margin to continue increasing, step 503 is performed, otherwise step 506 is performed.
503, the output value M of the on-line efficiency real-time optimization module is slowly increased by a first step length to further improve the cycle ratio of the input-output phase, and then step 504 is executed.
504, after step 503, the converter reaches a new steady state and the output voltage V of the four-switch buck-boost converter is reacquiredoInput voltage VinThe output value V of the output voltage closed-loop regulation module 403 of the converter's controllererStep 505 is continued.
505, judging the current output voltage value V of the four-switch converteroWhether to reduce or converter input voltage VinIf the change occurs, step 501 is executed to reset the threshold VerTHOtherwise, step 502 is executed to start a new round of adjustment.
506, if the judgment in the step 502 is negative, executing the step; this step reduces the output value M of the on-line real-time optimization module by a second step size to further reduce the cycle fraction value of the input-output stage. It should be noted that there is no specific size relationship between the second step size in step 506 and the first step size in step 503, for example, the first step size and the second step size may be equal. In addition, the first step length and the second step length can be fixed values, and can also be linear or nonlinear variable values, so that the high-efficiency operating point of the four-switch buck-boost converter can be quickly adjusted.
FIG. 6 is a schematic diagram of another embodiment of an online efficiency real-time optimization module, where the implementation method includes:
600, obtaining the output voltage V of the four-switch buck-boost converteroInput voltage VinTime value T of a fourth time period (clamping period) of a controller of the converter4。
601, setting a time value T of a fourth time period of the four-switch buck-boost converter4Upper threshold value T of4TH. Referring to fig. 2, fourth stage of the four-switch buck-boost converterThat is, a freewheeling stage in which the second switch S2 and the 4 th switch S4 of the buck-boost converter are turned on, the current of the inductor L freewheels between the second switch and the fourth switch, and the input voltage V is clamped in the clamping stageinAnd an output voltage VoOff, i.e. in the fourth phase, the input does not transfer energy to the output, which means that, from the point of view of the efficiency of the buck-boost converter, the shorter the time duration of the fourth phase, the better, so the upper threshold T4THShould be set to a lower value, typically 5% to 10% of the switching period is chosen.
602, determining the time value T of the clamping stage of the four-switch buck-boost converter4Whether the set threshold value T is reached4TH. If the set threshold value T is exceeded4THMeaning that the present four-switch buck-boost converter does not operate at the optimum efficiency point, i.e. the time value T2If there is still margin to continue increasing, step 603 is performed, otherwise step 606 is performed.
603, the output value M of the on-line efficiency real-time optimization module is slowly increased by a first step length to further improve the cycle ratio of the input-output stage, and then step 604 is performed.
604, after step 603, the converter reaches a new steady state and the output voltage V of the four-switch buck-boost converter is obtained againoInput voltage VinTime value T of the clamping phase of the controller of the converter4Execution continues at step 605.
605, judging the current output voltage value V of the four-switch converteroWhether to reduce or converter input voltage VinIf the change occurs, step 601 is executed to reset the threshold T4THOtherwise, step 602 is executed to start a new round of adjustment.
606, if the determination result in step 602 is negative, executing the step; this step reduces the output value M of the on-line real-time optimization module by a second step size to further reduce the cycle fraction value of the input-output stage. It should be noted that there is no specific size relationship between the second step size in step 606 and the first step size in step 603, for example, the first step size and the second step size may be equal. In addition, the first step size and the second step size can be fixed values, and can also be linear or nonlinear variable values, so that the high-efficiency operating point of the four-switch buck-boost converter can be rapidly adjusted.
To further illustrate the effect of the control method in improving efficiency, waveforms of the control method of the present invention and the existing control method under the same working condition are compared, as shown in fig. 7A and 7B, respectively. Under the conditions of 28V input voltage and 36V output voltage, the peak value and the effective value of the current of the inductor L of the control method are obviously smaller than those of the conventional control method. Fig. 8 further shows a comparison graph of the conversion efficiency of the four-switch buck-boost converter according to the embodiment of the present invention and the conversion efficiency of the power supply in the prior art under each load condition of loads 0.3A to 3.3A, which shows that the embodiment of the present invention can effectively improve the conversion efficiency of the power supply.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention.

Claims (9)

1. An online real-time efficiency optimization control method for a four-switch buck-boost converter is characterized in that one switching period of the four-switch buck-boost converter is sequentially divided into four stages: an input stage, an input-output stage, a follow current stage and a clamping stage; in the input stage, an input voltage and a ground end are respectively applied to two ends of the inductor; in the input-output stage, an input voltage and an output voltage are respectively applied to two ends of the inductor; in the afterflow stage, the output voltage and the ground end are respectively applied to two ends of the inductor, and in the clamping stage, the current of the inductor is kept unchanged; the control method is characterized by comprising the following steps:
when the four-switch lifting converter is in a stable state, the time value T of the input-output stage is enabled by adjusting the time value ratio M of the input stage and the input-output stage of the converter in real time on line2The ratio is maximized during the whole switching period and if the time value T of the input-output phase is maximized2The duty ratio is larger, and the output voltage has a falling change trend;
wherein, a phase time value T is input1And the input voltage sampling value VinOutput voltage sampling value VoThe maximum value of the output power of the four-switch buck-boost converter is determined;
sampling value V according to input voltageinOutput voltage sampling value VoClosed loop regulating value V of output voltageerAnd a clamp phase time value T4By clamping the phase time value T4Less than or equal to preset time length threshold upper limit T4THOr a closed-loop regulation value V of the output voltageerReaches the preset upper limit V of the output thresholderTHAnd calculating to obtain a time value ratio M for optimizing the target.
2. The on-line real-time efficiency optimization control method of the four-switch buck-boost converter of claim 1, further comprising:
s1, sampling value V of output voltageoAnd an output voltage reference value VorefPerforming subtraction operation, and performing proportional integral operation on the error value between the two values to obtain an output voltage closed-loop regulation value Ver，Ver＝(Kp+Ki/s)×(Voref-Vo) In the formula, KpAnd KiThe constants are respectively proportional and integral coefficients and are related to the specific working conditions of the four-switch buck-boost converter;
s2, sampling value V according to input voltageinOutput voltage sampling value VoClosed loop regulating value V of output voltageerAnd a clamp phase time value T4By clamping the stage time value T4Less than or equal to preset time length threshold upper limit T4THOr a closed-loop regulation value V of the output voltageerReaches the preset upper limit V of the output thresholderTHCalculating to obtain a time value ratio M for an optimization target;
s3, in the form of product or addition, by time value ratioM adjusting duration T of input-output phase2。
3. The on-line real-time efficiency optimization control method of the four-switch buck-boost converter according to claim 2, wherein in step S2, the duration of the clamping stage is T4Less than a preset upper limit T of the time length threshold4THIn order to optimize the objective, the process of calculating the time value ratio M includes the following steps:
s201, judging the clamping stage time value T of the four-switch buck-boost converter4Whether the time length exceeds the set upper limit T of the time length threshold4THIf yes, go to step S202, otherwise, go to step S204;
s202, increasing the time value ratio M by the first step length to increase the time value T of the input-output stage2And the converter reaches a new steady state;
s203, reacquiring the sampling value V of the input voltageinOutput voltage sampling value VoAnd a clamp phase time value T4Judging the output voltage sampling value V of the current four-switch converteroWhether or not to reduce or the value V of the sample of the input voltage of the converterinIf the change occurs, resetting the upper limit T of the time length threshold value4THReturning to the step S201, otherwise, directly returning to the step S201;
s204, reducing the time value ratio M by a second step length to reduce the time value T of the input-output stage2And the converter reaches a new steady state, and the process returns to step S201.
4. The on-line real-time efficiency optimization control method of the four-switch buck-boost converter according to claim 3, wherein the duration threshold upper limit T is4THThe value range of (1) is [ 5%. times.T ]s,10％×Ts]，TsIs the switching cycle duration.
5. The on-line real-time efficiency optimization control method of the four-switch buck-boost converter according to claim 2, wherein the method is characterized in thatIn step S2, the closed-loop regulation value V is outputtederReach the upper limit V of the preset output threshold valueerTHIn order to optimize the objective, the process of calculating the time value ratio M includes the following steps:
s211, setting an upper limit V of an output thresholderTH；
S212, judging the closed loop regulating value V of the output voltageerWhether the set threshold value V is reachederTHIf not, go to step S213, otherwise go to step S215;
s213, increasing the time value ratio M by the first step length to increase the time value T of the input-output stage2And the converter reaches a new steady state;
s214, the sampling value V of the input voltage is obtained againinOutput voltage sampling value VoAnd an output voltage closed loop regulation value VerJudging the current output voltage value V of the four-switch converteroWhether to reduce or the input voltage V of the converterinIf so, returning to step S211, otherwise returning to step S212;
s215, reducing the time value ratio M by a second step length to reduce the time value T of the input-output stage2And the converter reaches a new steady state, and returns to step S212.
6. The on-line real-time efficiency optimization control method of the four-switch buck-boost converter according to claim 5, wherein in step S211, the upper limit V of the output threshold is set according to the following formulaerTH：
Figure FDA0003553946910000021
7. The method of claim 2, wherein the step S3 is performed by adjusting the duration T of the I/O stage according to the time value ratio M2Process bagThe method comprises the following steps:
Figure FDA0003553946910000022
Figure FDA0003553946910000023
Figure FDA0003553946910000024
T4＝Ts-T1-T2-T3
in the formula, T1Is an input phase time value, T2Is the input-output phase time value, T3Is the value of the freewheel phase time, T4Is the value of the clamping phase time, TsIs a switching cycle value.
8. The on-line real-time efficiency optimization control method of the four-switch buck-boost converter of claim 2, wherein in step S3, the duration T of the input-output stage is adjusted in an additive manner by the time value ratio M2Comprises the following steps:
Figure FDA0003553946910000025
9. the utility model provides an online real-time efficiency optimization control device of four switch buck-boost converters which characterized in that, controlling means includes:
a subtractor for sampling value V of output voltageoAnd an output voltage reference value VorefCarrying out subtraction operation;
an output voltage closed loop regulation module, the input end of which is connected with the output end of the subtracter and used for sampling a value V of an output voltage samplingoAnd an output voltage reference value VorefThe error value between the two is subjected to proportional integral operation to obtain an output voltage closed loop regulating value Ver，Ver＝(Kp+Ki/s)×(Voref-Vo) In the formula, KpAnd KiThe constants are respectively proportional and integral coefficients and are related to the specific working conditions of the four-switch buck-boost converter;
the online efficiency implementation optimization module comprises four input ends which are respectively connected with the output end of the output voltage closed-loop regulation module, the input voltage sampling end, the output voltage sampling end and the T1～T4The clamping stage time value output end of the time period parameter calculation module is connected and used for sampling a value V according to the input voltageinOutput voltage sampling value VoClosed loop regulating value V of output voltageerAnd a clamp phase time value T4By clamping the stage time value T4Less than or equal to preset time length threshold upper limit T4THOr a closed-loop regulation value V of the output voltageerReaches the preset upper limit V of the output thresholderTHCalculating to obtain a time value ratio M for an optimization target;
T1～T4time period parameter calculation Module, T1～T4Three input ends of the time period parameter calculation module are respectively connected with an input voltage sampling end, an output end of the output voltage closed-loop regulation module and an output end of the online efficiency implementation optimization module, and T1～T4The time period parameter calculation module is used for calculating a time period parameter according to the input voltage sampling value VinClosed loop regulating value V of output voltageerCalculating the sum time value proportion M to obtain the time value T of the input stage1Time value T of input-output stage2Time value T of follow current stage3And a clamp phase time value T4Wherein, T1～T4The time period parameter calculation module adjusts the duration T of the input-output stage in a multiplication or addition mode by the time value proportion M2；
A PWM generation module for generating a PWM signal according to T1～T4Input stage time value T output by time period parameter calculation module1Time value T of input-output stage2Time value T of follow current stage3And a clamp phase time value T4And generating on-off control signals of four switches of the corresponding converter.
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