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CN109067178B - Control system and method for mode smooth switching of in-phase buck-boost converter - Google Patents

Control system and method for mode smooth switching of in-phase buck-boost converter Download PDF

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Publication number
CN109067178B
CN109067178B CN201811030119.8A CN201811030119A CN109067178B CN 109067178 B CN109067178 B CN 109067178B CN 201811030119 A CN201811030119 A CN 201811030119A CN 109067178 B CN109067178 B CN 109067178B
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buck
mode
power
time
boost
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CN109067178A (en
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陈晓飞
董一帆
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Shenzhen Huazhong University of Science and Technology Research Institute
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Shenzhen Huazhong University of Science and Technology Research Institute
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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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/14—Arrangements for reducing ripples from dc input or output

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention relates to a control technology of an in-phase four-tube buck-boost converter, in particular to a control system and a control method for mode smooth switching of the in-phase buck-boost converter. The principle of the invention is to clamp the minimum on-time of the power tubes SC and SB of the control circuit at tminSetting the maximum conduction time of the power tubes SA and SD as t in the Buck mode and the Boost modeAD0And the simultaneous conduction time of the power tubes SA and SD capable of realizing the solution is tAD1The control circuit realizes smooth mode switching. According to the control method, the conduction and turn-off time of the power tube is shortened in the switching process of the clamping mode, the influence of dead time on output voltage is eliminated, the ripple of the system is reduced, and the stability of the system is improved; the average inductive current in the Buck-Boost mode is reduced, and the efficiency is improved; the control method is simple to implement and can be used for any in-phase four-tube Buck-Boost converter controlled by a voltage mode.

Description

Control system and method for mode smooth switching of in-phase buck-boost converter
Technical Field
The invention relates to a control technology of an in-phase four-tube buck-boost converter, in particular to a control system and a control method for mode smooth switching of the in-phase buck-boost converter.
Background
The in-phase four-tube buck-boost converter can boost and buck timely under wide input voltage with low cost and high efficiency, and is widely applied to power supply of power amplifiers, photovoltaic inverters and mobile equipment.
In order to convert the voltage efficiently, the working mode of the in-phase four-tube Buck-Boost converter is divided into a Buck mode, a Buck-Boost mode and a Boost mode, wherein the Buck-Boost mode is used as the transition of the Buck mode and the Boost mode so as to reduce the peak generated in the mode switching process. Fig. 1A is a schematic circuit diagram of a control method for solving mode switching in the prior art, in which capacitors C1, C2 and C3 are off-chip capacitors, SW1 and SW2 are voltages across inductor L, SA and SC are power switches, and SB and SD are synchronous rectification power transistors. According to the requirements of input voltage VIN and output current, the control circuit controls the on-chip power tube to be switched on and off, and adjusts the output voltage VOUT. In the control circuit, a sampling voltage V is outputSAnd a reference voltage VREF as an input terminal of the error amplifier Amp. Error amplifierThe output signals are VC, VC and the overlapped ramp signals VBoost and VBuck are compared through a comparator COM1, and the period of the ramp signals VBoost and VBuck is TsAnd the output signal controls the power tubes SA, SB, SC and SD to be switched on and off through a driving circuit Driver.
As shown in FIG. 1B, VmaxAnd VLIs the maximum and minimum values of VBoost, VHAnd VminThe maximum and minimum values of VBuck. When the system works in a Buck mode, the error signal VC is only compared with VBUCK; when the system works in a Boost mode, VC is only compared with VBoost; when the system works in the Buck-Boost mode, VC is simultaneously compared with VBoost and VBuck. When the driving signal VO1 is at a high level/low level, the power transistor SA is turned on/off, and the power transistor SB is turned off/on; when the driving signal VO2 is at high/low level, the power transistor SD is turned on/off, and the power transistor SC is turned off/on.
However, due to the existence of the dead time of the power tube, the jump of voltage and current still exists in the switching process of the Buck mode and the Boost mode and the transition Buck-Boost mode, and the stability of the system is influenced. For example, when the system just enters the Buck-Boost mode from the Buck mode, because the low level duration of the signal VO2 for controlling the power tube SD is lower than the dead time, the parasitic capacitance of the power tube is not sufficiently charged and discharged, which causes the power tube SC to be turned off too soon, and the power tube SD is turned off too soon, the dc voltage conversion ratio remains unchanged, and thus, the output voltage drops along with the input voltage; as the input voltage continues to decrease, when the low-level duration of VO2 rises above the dead time, the parasitic capacitance of the power transistor charges and discharges over a threshold, the power transistors SC and SD switch normally, and the dc voltage conversion ratio rises, resulting in a jump in the output voltage. Similarly, the same is true for switching from the Buck-Boost mode to the Boost mode. Therefore, the influence of the dead time of the power tube on the output voltage must be eliminated to improve the stability of the output voltage during the mode switching.
Disclosure of Invention
The invention aims to provide a control system and a control method for mode smooth switching of an in-phase buck-boost converter, which can eliminate the influence of dead time of a power tube on output voltage in the mode switching process of a system and realize smooth mode switching.
The technical problem of the invention is mainly solved by the following technical scheme:
a control system for mode smooth switching of an in-phase Boost-Buck converter is characterized in that a clamping component is additionally arranged in a control circuit of the Buck-Boost converter, and the clamping component can clamp the minimum conduction time of power tubes SC and SB of an in-phase four-tube component in the Buck-Boost converter at tminSetting the maximum conduction time of the power tubes SA and SD as t in the Buck mode and the Boost modeAD0Wherein, tminAnd tAD0Setting the value of the power tube SA and the power tube SC to be conducted simultaneously, and setting the working time as tAC(ii) a The power tube SA and the power tube SD are conducted simultaneously, and the working time is tAD(ii) a The time for the power tube SB and the power tube SD to be simultaneously conducted is tBD(ii) a When the system is working in Buck mode, tAD+tBD＝Ts,tAC0; when the system is working in Boost mode, tAD+tBD＝TS,tAC+tAD＝Ts，tBD＝0，tAD0＝aTS；tmin＝bTs。
In the control system for mode smooth switching of the in-phase Buck-Boost converter, the clamping component comprises a clamping module and a pulse generation module which are sequentially connected, the input of the clamping component is connected with a comparator component of the Buck-Boost converter, and the output of the clamping component is connected with a driver of in-phase four tubes in the Buck-Boost converter.
In the control system for mode smooth switching of the in-phase buck-boost converter, the comparator component includes a comparator Com1, a comparator Com2, and a comparator Com 3; output sampling voltage V of sampling resistorSAnd a reference voltage VREF as an input terminal of the error amplifier Amp; the output signal of the error amplifier is the error signal VC, and the comparator Com1 compares VBUCKAnd VBOOSTComparing the sawtooth wave with an error signal VC, and outputting control signals VO1 and VO2 to a clamping component Clamp; the comparators Com2 and Com3 use the signal V respectivelyHSum signal VLComparing with the error signal VC to generate a control signal CON, and outputting to a clamping component Clamp, where VHIs a VBuckPeak value of sawtooth wave, VLIs a VBoostValley of the sawtooth wave.
In the control system for mode smooth switching of the in-phase buck-boost converter, the in-phase four-tube assembly includes: the power switch tube SA, the power switch tube SC, the synchronous rectification power tube SB and the synchronous rectification power tube SD are connected with the driving module; one end of an inductor L is simultaneously connected with a power switch tube SA and a synchronous rectification power tube SB, and the other end of the inductor L is simultaneously connected with a power switch tube SC and a synchronous rectification power tube SD; the output of the synchronous rectification power tube SD is connected with a load, and the regulated output voltage of the in-phase four-tube component is VOUT; the off-chip capacitor C1 is connected with the input of the same-phase four-tube component and grounded; the off-chip capacitor C2 is connected with the output of the same-phase four-tube component and grounded; the off-chip capacitor C3 is connected to the output of the error amplifier Amp and to ground.
In the control system for mode smooth switching of the in-phase buck-boost converter, tAD0＝0.85TS；tmin＝0.05Ts。
A control method for mode smooth switching of an in-phase Buck-Boost converter is characterized in that in a transition Buck-Boost mode, a power tube SA and an SD are conducted at the beginning, then the power tube SA and the SC are conducted, and finally a power tube SB and the SD are conducted in a switching period; and the minimum time for simultaneously conducting the power tubes SA and SC of the in-phase four-tube assembly in the Buck-Boost converter can be respectively clamped at t in one switching periodminThe minimum time for the power tubes SB and SD to be conducted simultaneously is clamped at tminSetting the maximum time of the power tubes SA and SD to be simultaneously conducted in the Buck mode and the Boost mode as tAD0Wherein, tminAnd tAD0The set value is defined, and the simultaneous conduction working time of the power tube SA and the power tube SC is tAC(ii) a The power tube SA and the power tube SD are conducted simultaneously for the working time tAD(ii) a The time for the power tube SB and the power tube SD to be simultaneously conducted is tBD(ii) a When the system is working in Buck mode, tAD+tBD＝Ts,tAC0; when the system is working in Boost mode, tAD+tBD＝Ts,tAC+tAD＝TS，tBD＝0，tAD0＝aTS；tmin＝bTs。
In the control method for mode smooth switching of the in-phase buck-boost converter, the power tube SA and the power tube SC are conducted simultaneously for the working time tAC(ii) a The power tube SA and the power tube SD are conducted simultaneously for the working time tAD(ii) a The time for the power tube SB and the power tube SD to be simultaneously conducted is tBD(ii) a When the system is working in Buck mode, tAD+tBD＝Ts,tACIs equal to 0 and has
Figure BDA0001789516150000041
Figure BDA0001789516150000042
Figure BDA0001789516150000043
Figure BDA0001789516150000044
Wherein M isVBuckDC voltage conversion ratio, M, representing the moment at which Buck mode is to be switched to Buck-Boost modeVBB1Denotes the DC voltage conversion ratio, M, at the time of just switching to Buck-Boost modeVBB2Indicating the DC voltage conversion ratio, M, when switching to Boost modeVBoostIndicating a direct-current voltage conversion ratio at the time of just switching to the Boost mode; t is tAD0Setting the maximum conduction time of the power tubes SA and SD in a Buck mode and a Boost mode; if the mode is smoothly switched, the formula (3) is equal to the formula (4), and the formula (5) is equal to the formula 6; if the two equations are respectively equal, the switching from the Buck mode or the Boost mode can be determinedAt the moment of Buck-Boost mode, the time interval for the power tubes SA and SD to be conducted simultaneously is ttD1。
In the control method for mode smooth switching of the in-phase Buck-Boost converter, along with the reduction of the input voltage, the working mode of the converter is changed from the Buck mode to the Buck-Boost mode and then to the Boost mode, and the method specifically includes:
step 1: error signal VCBelow VLWhen the system is working in Buck mode, the power tubes SA and SB control the voltage conversion ratio, where VLIs VBOOSTA valley of the sawtooth wave;
step 2: error signal VCSlowly rises above VLThe minimum time t of the simultaneous conduction of the clamping power tubes SA and SCminThe time of the simultaneous conduction of the power tubes SA and SD is from tAD0Instantaneously falls to tAD1The time of simultaneous conduction of SB and SD power tubes is dependent on VCSlowly rises and becomes smaller, and the time for the power tubes SA and SD to be simultaneously conducted is VCSlowly rises and becomes larger until tADFrom tAD1Rises to tAD0；
And step 3: error signal VCContinuing to rise, wherein the time for the power tubes SA and SD to be simultaneously conducted is always tAD0The time of the power tubes SA and SC conducting at the same time is not clamped any more, and is followed by VCThe power tube SB and SD are conducted simultaneously with VCRises and becomes smaller until tBDDecrease to tmin；
And 4, step 4: error signal VCContinues to rise and is lower than VHMinimum time t of simultaneous conduction of SB and SD of clamping power tubemin(ii) a The time of the power tubes SA and SC conducting simultaneously is VCSlowly rises and becomes larger, and the time for the power tubes SA and SD to be simultaneously conducted is VCSlowly rises and decreases until tADFrom tAD0Decrease to tAD1At the same time VCIs equal to VH(ii) a Wherein, VHIs VBUCKThe peak value of the sawtooth wave;
and 5: error signal VCContinuously rises and is higher than VHWhile the system is working at Boost working mode, the minimum time for simultaneous conduction of the SB and SD power tubes is not clamped any more; the time of the simultaneous conduction of the power tubes SA and SD is tAD1Rises to t instantaneouslyAD0The power tubes SC and SD control the voltage conversion ratio.
In the control method for mode smooth switching of the in-phase buck-boost converter, tAD0＝0.85TS；tmin＝0.05ts。
Therefore, the invention has the following advantages: according to the control method, the conduction and turn-off time of the power tube is shortened in the switching process of the clamping mode, the influence of dead time on output voltage is eliminated, the ripple of the system is reduced, and the stability of the system is improved; the average inductive current in the Buck-Boost mode is reduced, and the efficiency is improved; the control method is simple to implement and can be used for any in-phase four-tube Buck-Boost converter controlled by a voltage mode.
Drawings
FIG. 1A is a control method of a conventional in-phase four-tube Buck-Boost converter.
Fig. 1B is a waveform diagram illustrating a control method of a conventional in-phase four-tube Buck-Boost converter.
FIG. 2 is a relationship between error output voltage and DC conversion ratio of an in-phase four-tube Buck-Boost converter.
FIG. 3 is a key control module that eliminates the effects of dead time.
The control method proposed in fig. 4A switches the key waveforms from Buck mode to Buck-Boost mode.
The control method proposed in fig. 4B switches the key waveforms from Buck-Boost mode to Boost mode.
Fig. 5 is a system architecture diagram of the proposed control method, taking LED constant current driving as an example.
Detailed Description
The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings.
Example (b):
the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to only such embodiments. The invention is intended to cover any alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention. In the following detailed description of the preferred embodiments of the present invention, specific details are set forth in order to provide a thorough understanding of the present invention, and it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.
The input voltage of a lithium battery is slowly reduced with the use time, and is generally reduced from 4.7V to 2.7V. Because the duty ratio of the four power switching tubes cannot be suddenly changed, when the input voltage is reduced, the output voltage is also reduced, the error signal VC is increased, and then the duty ratio is adjusted to stabilize the output voltage. Under the stable working condition, when the input voltage generates a small change delta VIN, the change delta VO of the output voltage is approximately in a linear relation with the small change delta VIN of the input voltage, and the change delta VC of the error signal and the change delta VO of the output voltage are also approximately in a linear change. Therefore, as shown in FIG. 2, during the converter mode switching process, if the voltage conversion ratio M is at two critical points A and BVSmooth and continuous, the converter realizes smooth mode switching.
As shown in fig. 1A, the dc characteristics of the in-phase four-tube Buck-Boost converter can be obtained according to volt-second balance and charge conservation, as shown in equations (1) and (2):
Figure BDA0001789516150000071
Figure BDA0001789516150000072
wherein, ILFor the average current through the inductor, IOIs the load current. The Buck-Boost mode is divided into three working states, namely that the power tube SA and the power tube SC are conducted simultaneously, and the working time is tAC(ii) a The power tube SA and the power tube SD are conducted simultaneously, and the working time is tAD(ii) a The time for the power tube SB and the power tube SD to be simultaneously conducted is tBD. When the system is working in Buck mode, tAD+tBD＝Ts,tAC＝0(ii) a When the system is working in Boost mode, tAD+tBD＝Ts,tAC+tAD＝Ts，tBD0. When the load is constant, if tAD+tBDIs far greater than tACThe average current I of the inductor can be reducedL。
As shown in fig. 2, it is difficult to determine an accurate dc conversion voltage ratio M at two critical points a and B due to the presence of dead timeVResulting in a DC-to-DC conversion voltage ratio MVWith respect to error signal VCThe curve of (2) is discontinuous.
The invention clamps the minimum conduction time t of the power tubes SC and SBminTo ensure MVContinuous and smooth. Wherein M in the left neighborhood of the point A and the right neighborhood of the point AVThe expression of (1) is (3) (4); m in left neighborhood of point B and right neighborhood of point BVIs (5) (6):
Figure BDA0001789516150000081
Figure BDA0001789516150000082
Figure BDA0001789516150000083
Figure BDA0001789516150000084
wherein M isVBuckIndicating the DC voltage conversion ratio, M, at which Buck mode is to be switched to Buck-Boost modeVBB1Indicating the DC voltage conversion ratio, M, just switched to Buck-Boost modeVBB2Indicating the DC voltage conversion ratio, M, to be switched to Boost modeVBoostIndicating the dc voltage conversion ratio just switched to Boost mode. t is tAD0When the set power tubes SA and SD are conducted at maximum in Buck mode and Boost modeAnd (3) removing the solvent. When the mode is smoothly switched, the equations (3) and (4) are equal to each other, and the equations (5) and (6) are equal to each other. When the two equations are respectively equal, the time interval t at which the power tubes SA and SD are simultaneously conducted at the moment of switching from the Buck mode or the Boost mode to the Buck-Boost mode can be determinedAD1。
That is, as long as the control circuit is able to clamp the minimum on-time of the power transistors SC and SB at tminSetting the maximum conduction time of the power tubes SA and SD as t in the Buck mode and the Boost modeAD0And the simultaneous conduction time of the power tubes SA and SD capable of realizing the solution is tAD1The control circuit realizes smooth mode switching.
The following are specific examples. While the invention has been described in detail with respect to its preferred embodiments for a thorough understanding of the invention, it will be apparent to those skilled in the art that the invention may be practiced without these specific details.
VREF is the reference voltage, V, as shown in FIG. 3STo output the current sampling signal, the comparator Com1 compares VBUCKAnd VBOOSTThe sawtooth wave is compared with the error signal VC and outputs control signals VO1 and VO 2. Comparators Com2 and Com3 use V respectivelyHAnd VLThe control signal CON is generated to determine the operation mode in comparison with the error signal VC. When CON is at high level, the system works in a Buck-Boost mode, and the Pulse generation module Pulse and the clamping module Clamp start working. VCL1 and VCL2 are clamp signals, and the low level pulse width is clamped to tmin. Output signals of the clamping module Clamp are VAB and VCD, when the driving signal VAB is at a high level/a low level, the power tube SA is switched on/off, and the power tube SB is switched off/on; when the driving signal VCD is at a high level/a low level, the power transistor SD is turned on/off, and the power transistor SC is turned off/on.
Referring to FIG. 4A, it is illustrated that as VIN slowly decreases, the converter switches from Buck mode to Buck mode
And working process of Buck-Boost mode. When the error signal VC is higher than VLWhen CON is high, Pulse generator Pulse and Clamp circuit Clamp are enabled.
Converter slave BuThe beginning stage of switching the ck mode to the Buck-Boost mode starts to delay T from the crossing time of the rising slopes of VC and VBoosts-tminA falling edge of VCL1 is generated, at which time the duration of VC above VBoost is less than tminVo2 is clamped high. As the error signal VC continues to rise, the falling edge of VCL1 is determined by the falling edge of VBoost when the falling edge of VCL1 coincides with the falling edge of VBoost during a period; meanwhile, when the duration of VC higher than VBoost is longer than tminVO2 is no longer clamped and transitions high and low as shown in fig. 4A, i.e., VC is low above VBoost and high otherwise. VCL1 and VO2 derive the VCD signals via a logical and circuit.
The converter is switched from the Buck mode to the Buck-Boost mode at the beginning, and the time interval between the rising ramp crossing moment and the falling ramp crossing moment of the error signal VC and the VBoost is recorded as t1(t), starting delay t from the rising ramp crossing time of VC and VBoost2(t)＝(Ts-tAD0)-t1(t) produces a falling edge of VCL 2. As the error signal VC continues to rise, the rising edge of VCL2 is determined by the falling edge of VBuck, when the rising edge of VCL2 coincides with the falling edge of VBuck within a period. VO1 makes high-low transitions as shown in fig. 4A, i.e., VC is high above VBuck and low otherwise. VCL2 and VO1 obtain the VAB signal through a logical and circuit.
The operation of switching from the Buck-Boost mode to the Boost mode is described with reference to fig. 4B. At the initial stage of mode switching, VO1 performs high-low level switching as shown in fig. 4B, that is, VC is high level when being higher than VBuck, otherwise, it is low level; as the error signal VC continues to rise, the duration of VC being below VBuck is less than t during a switching periodminThen VO1 is forced high. VCL2 switches as shown in FIG. 4B, i.e., the falling edge of VCL2 occurs at the time of the rising ramp crossing of error signals VC and VBuck, and passes through fixed tminThe time switches to a high level. VCL2 and VO1 obtain the VAB signal through a logical and circuit.
The time interval between the rising ramp crossing time of the error signals VC and VBoost and the falling edge time of VBuck is recorded as t3(t), falling edge delay t from VBuckAD0-t3(t) produces a falling edge of VCL 1. At the same time, VO2 makes high-low level transition as shown in fig. 4B, i.e. VC is low when higher than VBoost, otherwise it is high. VCL1 and VO2 derive the VCD signals via a logical and circuit.
When the error signal VC is greater than or equal to VHWhen the control signal CON is at low level, the Pulse generator Pulse and the clamping circuit Clamp are closed; and the converter enters a Boost working mode, and the transition working mode is ended.
Referring to fig. 5, a clamp circuit is designed in the dashed line block diagram of the system architecture to ensure smooth mode switching of the system.
The foregoing shows and describes the general principles and features of the present invention, together with the advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Claims (8)

1. A control system for mode smooth switching of an in-phase Boost-Buck converter is characterized in that a clamping component is additionally arranged in a control circuit of the Buck-Boost converter, and the clamping component can clamp the minimum conduction time of power tubes SC and SB of an in-phase four-tube component in the Buck-Boost converter at tminSetting the maximum conduction time of the power tubes SA and SD as t in the Buck mode and the Boost modeAD0Wherein, tminAnd tAD0Setting the value of the power tube SA and the power tube SC to be conducted simultaneouslyTime tAC(ii) a The power tube SA and the power tube SD are conducted simultaneously, and the working time is tAD(ii) a The time for the power tube SB and the power tube SD to be simultaneously conducted is tBD(ii) a When the system is working in Buck mode, tAD+tBD＝Ts,tAC0; when the system is working in Boost mode, tAC+tAD＝Ts，tBD＝0，tAD0＝aTS；tmin＝bTsThe input of the clamping component is connected with a comparator component of the Buck-Boost converter, and the output of the clamping component is connected with a driver of a same-phase four-tube in the Buck-Boost converter; the comparator assembly comprises a comparator Com1, a comparator Com2, and a comparator Com 3; output sampling voltage V of sampling resistorSAnd a reference voltage VREF as an input terminal of the error amplifier Amp; the output signal of the error amplifier is the error signal VC, and the comparator Com1 compares VBUCKAnd VBOOSTComparing the sawtooth wave with an error signal VC, and outputting control signals VO1 and VO2 to a clamping component Clamp; the comparators Com2 and Com3 use the signal V respectivelyHSum signal VLComparing with the error signal VC to generate a control signal CON, and outputting to a clamping component Clamp, where VHIs a VBuckPeak value of sawtooth wave, VLIs a VBoostValley of the sawtooth wave.
2. The control system of claim 1, wherein the clamping assembly comprises a clamping module and a pulse generation module connected in series.
3. The control system for smooth switching of the modes of an in-phase buck-boost converter as claimed in claim 1, wherein the in-phase quad-tube assembly comprises: the power switch tube SA, the power switch tube SC, the synchronous rectification power tube SB and the synchronous rectification power tube SD are connected with the driving module; one end of an inductor L is simultaneously connected with a power switch tube SA and a synchronous rectification power tube SB, and the other end of the inductor L is simultaneously connected with a power switch tube SC and a synchronous rectification power tube SD; the output of the synchronous rectification power tube SD is connected with a load, and the regulated output voltage of the in-phase four-tube component is VOUT; the off-chip capacitor C1 is connected with the input of the same-phase four-tube component and grounded; the off-chip capacitor C2 is connected with the output of the same-phase four-tube component and grounded; the off-chip capacitor C3 is connected to the output of the error amplifier Amp and to ground.
4. The control system of claim 1, wherein t is tAD0＝0.85TS；tmin＝0.05Ts。
5. A control method for mode smooth switching of an in-phase Buck-Boost converter is characterized in that in a transitional Buck-Boost mode, power tubes SA and SD are conducted at the beginning, then the power tubes SA and SC are conducted, finally the power tubes SB and SD are conducted, and the minimum time for conducting the power tubes SA and SC of an in-phase four-tube assembly in the Buck-Boost converter at the same time can be clamped at t in one switching periodminThe minimum time for the power tubes SB and SD to be conducted simultaneously is clamped at tminSetting the maximum time of the power tubes SA and SD to be simultaneously conducted in the Buck mode and the Boost mode as tAD0Wherein, tminAnd tAD0The set value is defined, and the simultaneous conduction working time of the power tube SA and the power tube SC is tAC(ii) a The power tube SA and the power tube SD are conducted simultaneously for the working time tAD(ii) a The time for the power tube SB and the power tube SD to be simultaneously conducted is tBD(ii) a When the system is working in Buck mode, tAD+tBD＝Ts,tAC0; when the system is working in Boost mode, tAC+tAD＝Ts，tBD＝0，tAD0＝aTS；tmin＝bTs。
6. The method as claimed in claim 5, wherein the power transistor SA and the power transistor SC are turned on simultaneously for a period of time tAC(ii) a The power tube SA and the power tube SD are conducted simultaneously for the working time tAD(ii) a Power tube SB sum workThe time for simultaneous conduction of the rate tubes SD is tBD(ii) a When the system is working in Buck mode, tAD+tBD＝Ts,tACIs equal to 0 and has
Figure FDA0002564626130000031
Figure FDA0002564626130000032
Figure FDA0002564626130000033
Figure FDA0002564626130000034
Wherein M isVBuckDC voltage conversion ratio, M, representing the moment at which Buck mode is to be switched to Buck-Boost modeVBB1Denotes the DC voltage conversion ratio, M, at the time of just switching to Buck-Boost modeVBB2Indicating the DC voltage conversion ratio, M, when switching to Boost modeVBoostIndicating a direct-current voltage conversion ratio at the time of just switching to the Boost mode; t is tAD0Setting the maximum conduction time of the power tubes SA and SD in a Buck mode and a Boost mode; if the modes are switched smoothly, equation (3) and equation (4) are equal, equation 5 and equation 6 are equal, and it can be determined that the time interval of the simultaneous conduction of the power tubes SA and SD at the moment of switching from the Buck mode or the Boost mode to the Buck-Boost mode is tAD1。
7. The method as claimed in claim 6, wherein as the input voltage decreases, the operating mode of the converter changes from Buck mode to Buck-Boost mode to Boost mode, and specifically comprises:
step 1: error of the measurementSignal VCBelow VLWhen the system is working in Buck mode, the power tubes SA and SB control the voltage conversion ratio, where VLIs VBOOSTA valley of the sawtooth wave;
step 2: error signal VCSlowly rises above VLThe minimum time t of the simultaneous conduction of the clamping power tubes SA and SCminThe time of the simultaneous conduction of the power tubes SA and SD is from tAD0Instantaneously falls to tAD1The time of simultaneous conduction of SB and SD power tubes is dependent on VCSlowly rises and becomes smaller, and the time for the power tubes SA and SD to be simultaneously conducted is VCSlowly rises and becomes larger until tADFrom tAD1Rises to tAD0；
And step 3: error signal VCContinuing to rise, wherein the time for the power tubes SA and SD to be simultaneously conducted is always tAD0The time of the power tubes SA and SC conducting at the same time is not clamped any more, and is followed by VCThe power tube SB and SD are conducted simultaneously with VCRises and becomes smaller until tBDDecrease to tmin；
And 4, step 4: error signal VCContinues to rise and is lower than VHMinimum time t of simultaneous conduction of SB and SD of clamping power tubemin(ii) a The time of the power tubes SA and SC conducting simultaneously is VCSlowly rises and becomes larger, and the time for the power tubes SA and SD to be simultaneously conducted is VCSlowly rises and decreases until tADFrom tAD0Decrease to tAD1At the same time VCIs equal to VH(ii) a Wherein, VHIs VBUCKThe peak value of the sawtooth wave;
and 5: error signal VCContinuously rises and is higher than VHWhen the system works in a Boost working mode, the minimum time for simultaneous conduction of the SB and SD power tubes is not clamped any more; the time of the simultaneous conduction of the power tubes SA and SD is tAD1Rises to t instantaneouslyAD0The power tubes SC and SD control the voltage conversion ratio.
8. The method as claimed in claim 5, wherein the method comprises the step of controlling mode smooth switching of the in-phase buck-boost converterIs characterized in that tAD0＝0.85TS；tmin＝0.05Ts。
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