CN114094826A - Method, system, equipment and medium for improving efficiency of buck-boost controller - Google Patents
Method, system, equipment and medium for improving efficiency of buck-boost controller Download PDFInfo
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- CN114094826A CN114094826A CN202111060590.3A CN202111060590A CN114094826A CN 114094826 A CN114094826 A CN 114094826A CN 202111060590 A CN202111060590 A CN 202111060590A CN 114094826 A CN114094826 A CN 114094826A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
- H02M3/1582—Buck-boost converters
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- 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
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Abstract
The invention relates to a method, a system, equipment and a medium for improving the efficiency of a buck-boost controller. And if the buck-boost controller is in a discharging state, opening the first switch tube and the third switch tube, closing the second switch tube and the fourth switch tube until the inductive current is zero, closing the first switch tube, and opening the second switch tube after delaying the first time until the light-load working mode is exited. The invention can skillfully utilize the time-sharing opening and closing of the four switching tubes, optimize the working mode in the light-load working mode and obviously improve the efficiency of the buck-boost controller in the light-load working mode.
Description
Technical Field
The invention relates to the technical field of control of a buck-boost controller, in particular to a method, a system, equipment and a medium for improving the efficiency of the buck-boost controller in a light-load working mode.
Background
When the load is small, the buck-boost controller (BUCKBOOST controller) is added into a light-load working mode to reduce the power consumption of the system. After entering a light-load working mode, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube in the buck-boost controller stop switching to reduce power consumption. And after entering a light-load working mode, immediately turning off the first switching tube, the second switching tube, the third switching tube and the fourth switching tube. Or after entering a light-load working mode, the zero current detection circuit is adopted, and when the inductive current is detected to be reduced to zero, the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are immediately turned off. That is, the two methods cannot ensure that the inductor current is zero when the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are turned off, and when the inductor current is not zero, the parasitic capacitances at the two ends of the inductor and the inductor will generate ringing, which causes the inductor current to oscillate. In addition, if the buck-boost controller works in a light-load working mode for a long time, the lower tubes of the second switching tube and the third switching tube are closed, the bootstrap capacitor cannot be charged, and the buck-boost controller may not work normally. Based on the two problems, the efficiency of the buck-boost controller working in the light-load working mode can be greatly reduced.
Therefore, how to improve the efficiency of the buck-boost controller in the light-load working mode is a problem which needs to be solved urgently at present.
Disclosure of Invention
The invention aims to provide a method, a system, equipment and a medium for improving the efficiency of a buck-boost controller, which optimize the working mode in a light-load working mode so as to improve the efficiency of the buck-boost controller in the light-load working mode.
In order to achieve the purpose, the invention provides the following scheme:
a method of increasing the efficiency of a buck-boost controller, the method comprising:
judging the state of the buck-boost controller when the buck-boost controller enters a light-load working mode;
if the buck-boost controller is in a charging state, opening a second switching tube and a fourth switching tube, and closing a first switching tube and a third switching tube; the fourth switching tube is closed until the inductive current is zero; after delaying the first time, opening the third switch tube until the light-load working mode is exited; the first time is the time when the inductive current returns to zero again;
if the buck-boost controller is in a discharging state, opening the first switching tube and the third switching tube, and closing the second switching tube and the fourth switching tube; turning off the first switching tube until the inductive current is zero; and after delaying the first time, opening the second switch tube until the light-load working mode is exited.
A system to improve the efficiency of a buck-boost controller, the system comprising:
the judging module is used for judging the state of the buck-boost controller when the buck-boost controller enters a light-load working mode;
the charging state control module is used for opening the second switching tube and the fourth switching tube and closing the first switching tube and the third switching tube if the buck-boost controller is in a charging state; the fourth switching tube is closed until the inductive current is zero; after delaying the first time, opening the third switch tube until the light-load working mode is exited; the first time is the time when the inductive current returns to zero again;
the discharge state control module is used for opening the first switching tube and the third switching tube and closing the second switching tube and the fourth switching tube if the buck-boost controller is in a discharge state; turning off the first switching tube until the inductive current is zero; and after delaying the first time, opening the second switch tube until the light-load working mode is exited.
An apparatus for improving the efficiency of a buck-boost controller, comprising:
a processor; and
a memory having computer-readable program instructions stored therein,
wherein the method is performed when the computer readable program instructions are executed by the processor.
A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the above-mentioned method.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
according to the method, the system, the equipment and the medium for improving the efficiency of the buck-boost controller, when the light-load working mode is entered, the state of the buck-boost controller is judged firstly, if the buck-boost controller is in a charging state, the second switching tube and the fourth switching tube are opened, the first switching tube and the third switching tube are closed until the inductive current is zero, the fourth switching tube is closed, and the third switching tube is opened after the first time is delayed until the light-load working mode is exited. And if the buck-boost controller is in a discharging state, opening the first switch tube and the third switch tube, closing the second switch tube and the fourth switch tube until the inductive current is zero, closing the first switch tube, and opening the second switch tube after delaying the first time until the light-load working mode is exited. And then no matter be in the charged state or under the discharge state, after getting into the light load mode of operation, the homoenergetic is ingenious to be utilized the timesharing of four switch tubes and is opened and close, optimizes the working method under the light load mode of operation for the inductive current reduces to zero, prevents inductive current ringing phenomenon, and can charge for the bootstrap capacitor, prevents the unable problem of working of buck-boost controller, can show the efficiency that improves buck-boost controller under the light load mode of operation.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts. The following drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
FIG. 1 is a process flow diagram of the method provided in example 1 of the present invention;
fig. 2 is a schematic structural diagram of a buck-boost controller according to embodiment 1 of the present invention;
fig. 3 is a schematic diagram of duty ratio generation provided in embodiment 1 of the present invention;
FIG. 4 is a graph of the inductor current waveform during a single cycle as provided in example 1 of the present invention;
fig. 5 is a waveform diagram of an inductor current in different operating modes according to embodiment 1 of the present invention;
fig. 6 is a diagram of output voltage waveforms and inductor current waveforms in different operating modes in a charging state according to embodiment 1 of the present invention;
fig. 7 is a system block diagram of the system provided in embodiment 2 of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
As used herein, the terms "comprises" and "comprising" are intended to be inclusive and mean that there may be additional steps or elements other than the listed steps or elements.
Flow charts are used in the present invention to illustrate the operations performed by a system according to embodiments of the present invention. It should be understood that the preceding or following operations are not necessarily performed in the exact order in which they are performed. Rather, the various steps may be processed in reverse order or simultaneously, as desired. Meanwhile, other operations may be added to the processes, or a certain step or several steps of operations may be removed from the processes.
The invention aims to provide a method, a system, equipment and a medium for improving the efficiency of a buck-boost controller, which optimize the working mode in a light-load working mode so as to improve the efficiency of the buck-boost controller in the light-load working mode.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Example 1:
the embodiment is used to provide a method for improving the efficiency of a buck-boost controller, as shown in fig. 1, the method includes:
s1: judging the state of the buck-boost controller when the buck-boost controller enters a light-load working mode;
s2: if the buck-boost controller is in a charging state, opening a second switching tube and a fourth switching tube, and closing a first switching tube and a third switching tube; the fourth switching tube is closed until the inductive current is zero; after delaying the first time, opening the third switch tube until the light-load working mode is exited; the first time is the time when the inductive current returns to zero again;
s3: if the buck-boost controller is in a discharging state, opening the first switching tube and the third switching tube, and closing the second switching tube and the fourth switching tube; turning off the first switching tube until the inductive current is zero; and after delaying the first time, opening the second switch tube until the light-load working mode is exited.
Before describing the method provided by the embodiment, the principle and the working mode of the buck-boost controller of the embodiment are described:
as shown in fig. 2, a schematic structural diagram of the buck-boost controller used in the present embodiment is shown. The buck-boost controller used in this embodiment is a four-switch-tube buck-boost controller. The buck-boost controller of the present embodiment has two states, namely a charging state and a discharging state, and when the buck-boost controller is in the charging state, VBUS in fig. 2 is equal to the input voltage VinVBAT is equal to the output voltage Vout(ii) a VBAT in FIG. 2 is equal to the input voltage V when the buck-boost controller is in the discharging stateinVBUS is equal to the output voltage Vout. M1, M2, M3 and M4 are respectively a first switch tube, a second switch tube and a fourth switch tubeThe high-voltage switch comprises a three-switch tube and a fourth switch tube, D1, D2, D3 and D4 are parasitic body diodes of a first switch tube M1, a second switch tube M2, a third switch tube M3 and a fourth switch tube M4 respectively, HS1, LS1, LS2 and HS2 are switch tube control signals of the first switch tube M1, the second switch tube M2, the third switch tube M3 and the fourth switch tube M4 respectively, and L is inductance. C1 and C2 are two bootstrap capacitors connected between SW (including SW1 and SW2) and the drive circuit Logic&Between the drives, it is used as the power source of the driving circuit. The driving circuit is used for generating switching tube control signals of the four switching tubes so as to control the switching tubes to be switched on or switched off.
The buck-boost controller of the embodiment has two working modes, namely a normal working mode and a light-load working mode. Specifically, the normal operating mode is a Pulse Width Modulation (PWM) operating mode, and the light-load operating mode is a Pulse Frequency Modulation (PFM) operating mode. The judgment condition for entering the PFM working mode from the PWM working mode is that the average inductive current is smaller than a first preset threshold value, and the judgment condition for entering the PWM working mode from the PFM working mode is that the output voltage V is outputoutAnd when the current value is smaller than the second preset threshold value, judging whether the buck-boost controller is in a normal working mode or a light-load working mode currently through the inductive current and the output voltage.
When the buck-boost controller works in the PWM working mode, VinGreater than VoutThe BUCK-boost controller works in a BUCK period (BUCK period); vinLess than VoutIf so, the BOOST-buck controller works in a BOOST period (BOOST period); vinIs close to VoutAnd the buck-BOOST controller works in a buck-BOOST BUCKBOOST period, the BOOST period and the buck period work alternately, and the buck-BOOST controller is processed in a BOOST period mode in the BUCKBOOST period. If the boost-buck controller works in the boost period when entering the PFM working mode from the PWM working mode, the boost-buck controller still works in the boost period when entering the PWM working mode from the PFM working mode, if the boost-buck controller works in the buck period when entering the PFM working mode from the PWM working mode, the boost-buck controller still works in the buck period when entering the PWM working mode from the PFM working mode。
As shown in fig. 2, the buck-boost controller further includes a buck boost loop Control module for generating a loop Control signal (Vc), where the loop Control signal is a variable Voltage signal used to Control the output Voltage to be stable. After output from the BUCKBOOST loop control module, Vc is changed into two signals, namely a BOOST loop control signal Vc _ BOOST and a BUCK loop control signal Vc _ BUCK. The BOOST ramp module is used for generating a BOOST ramp (BOOST ramp) in a BOOST period, and the BUCK ramp module is used for generating a BUCK ramp (BUCK ramp) in a BUCK period, wherein each period generates a ramp signal. If the BUCK loop control signal Vc _ BUCK intersects with the BUCK slope in one period and the BOOST loop control signal Vc _ BOOST does not intersect with the BOOST slope, the current BUCK-BOOST controller is in the BUCK period, the BUCKPWM comparator generates a BUCK duty ratio, concretely, the output of the BUCKPWM comparator is high when the input of the positive end of the BUCKPWM comparator is the BUCK loop control signal Vc _ BUCK and the input of the negative end of the BUCKPWM comparator is the BUCK slope, and the output of the BUCKPWM comparator is high when the BUCK loop control signal Vc _ BUCK is larger than the BUCK slope; when the BUCK loop control signal Vc _ BUCK is smaller than the BUCK slope, the output of the BUCKPWM comparator is low. If the voltage reduction loop control signal Vc _ BUCK is not intersected with the voltage reduction slope in one period, and the voltage BOOST loop control signal Vc _ BOOST is intersected with the voltage BOOST slope, the current voltage reduction controller is in the voltage BOOST period, the BOOSTPWM comparator generates a BOOST duty ratio, specifically, the positive end input of the BOOST PWM comparator is the voltage BOOST loop control signal Vc _ BOOST, the negative end input of the BOOST PWM comparator is the voltage BOOST slope, and when the voltage BOOST loop control signal Vc _ BOOST is larger than the voltage BOOST slope, the output of the BOOST PWM comparator is high; when the BOOST loop control signal Vc _ BOOST is less than the BOOST ramp, the BOOST PWM comparator output is low. The output ends of the BUCKPWM comparator and the BOOSTPWM comparator are connected with the driving circuit.
The four-switch tube BUCK BOOST controller based on the average current mode architecture used in this embodiment generates the duty cycle by the intersection of the loop control signal Vc and the ramp, and different loop control signals intersect different ramps in one period to generate the duty cycles of BUCK and BOOST respectively, as shown in fig. 3, which is a schematic diagram for generating the duty cycle.
FIG. 3(a) is a schematic diagram of generating BUCK duty cycle, the positive input of BUCK PWM comparator is Vc _ BUCK, the negative input is BUCK slope, when Vc _ BUCK is larger than BUCK slope, the output of BUCK PWM comparator is high; when Vc _ BUCK is smaller than BUCK slope, BUCKPWM comparator output is low. When the output of the BUCKPWM comparator is high, the driving circuit controls HS1 to be high and LS1 to be low, namely M1 is turned on and M2 is turned off; when the output of the BUCKPWM comparator is low, the driving circuit controls HS1 to be low, LS1 to be high, namely M1 is closed, M2 is opened, and for BUCK, M1 is duty ratio when being opened, so that BUCK duty ratio information is generated when the output of the BUCKPWM comparator is high, namely when Vc _ BUCK is larger than BUCK slope, the BUCK duty ratio information is generated.
FIG. 3(b) is a schematic diagram of generating a BOOST duty cycle, where the positive input of the BOOST PWM comparator is Vc _ BOOST, the negative input is a BOOST ramp, and when Vc _ BOOST is greater than the BOOST ramp, the BOOST PWM comparator output is high; when Vc _ BOOST is less than the BOOST ramp, the BOOST PWM comparator output is low. When the output of the BOOST PWM comparator is high, the driving circuit controls HS2 to be high and LS2 to be low, namely M4 is turned on and M3 is turned off; when the BOOST PWM comparator output is low, the driver circuit controls HS2 to be low and LS2 to be high, i.e., M4 is off and M3 is on. For BOOST, M3 is duty cycle when it is on, so the BOOST PWM comparator output is low to generate BOOST duty cycle information, i.e. when Vc _ BOOST is less than the BOOST ramp, the BOOST duty cycle information is generated.
Based on the principle, when the buck-boost controller is in the PWM working mode, the switching tube is controlled as follows: when the BOOST-buck controller works in a BOOST cycle, and Vc _ BOOST is smaller than a BOOST slope at the moment, generating BOOST duty ratio information, if the BOOST-buck controller is in a charging state, opening a first switching tube M1 and a fourth switching tube M4, and closing a second switching tube M2 and a third switching tube M3 before the BOOST slope intersects with a BOOST loop control signal; after the boost ramp intersects with the boost loop control signal, the first switching tube M1 and the third switching tube M3 are opened, and the second switching tube M2 and the fourth switching tube M4 are closed. If the boost-buck controller is in a discharging state, before the boost ramp intersects with the boost loop control signal, opening the first switching tube M1 and the fourth switching tube M4, and closing the second switching tube M2 and the third switching tube M3; after the boost ramp intersects with the boost loop control signal, the second switching tube M2 and the fourth switching tube M4 are opened, and the first switching tube M1 and the third switching tube M3 are closed.
When the BUCK-boost controller works in a BUCK period, and Vc _ BUCK is larger than a BUCK slope at the moment, BUCK duty ratio information is generated, if the BUCK-boost controller is in a charging state, before the BUCK slope intersects with a BUCK loop control signal, a first switching tube M1 and a fourth switching tube M4 are opened, and a second switching tube M2 and a third switching tube M3 are closed; after the buck ramp crosses the buck loop control signal, the second switch transistor M2 and the fourth switch transistor M4 are opened, and the first switch transistor M1 and the third switch transistor M3 are closed. If the buck-boost controller is in a discharging state, before the buck ramp intersects with the buck loop control signal, the first switching tube M1 and the fourth switching tube M4 are opened, and the second switching tube M2 and the third switching tube M3 are closed; after the buck ramp crosses the buck loop control signal, the first switch transistor M1 and the third switch transistor M3 are opened, and the second switch transistor M2 and the fourth switch transistor M4 are closed.
According to the above control method of the switching tube, when the buck-boost controller is in the PWM operating mode, the inductor current waveform corresponding to the buck period is shown in fig. 4(a), and the inductor current waveform corresponding to the boost period is shown in fig. 4 (b).
Before determining the state of the buck-boost controller when entering the light-load working mode, the method of this embodiment further includes: judging whether the inductive current is smaller than a first preset threshold value in real time in the working process of the buck-boost controller; if so, the buck-boost controller enters a light-load working mode; if not, the buck-boost controller keeps the PWM working mode. And then whether the current buck-boost controller enters a light-load working mode is determined in real time according to the detection of the inductive current.
In the prior art, when entering the PFM operation mode, M1, M2, M3, and M4 stop the switch to reduce power consumption. In general, after entering the PFM operating mode, M1, M2, M3, and M4 are turned off immediately, or after determining that the PFM operating mode is entered, a zero current detection circuit is used, and when the current is detected to drop to 0, M1, M2, M3, and M4 are turned off immediately. That is, neither of the above two methods can ensure that the inductor current is zero when M1, M2, M3, and M4 are turned off, and when the inductor current is not zero, the parasitic capacitance between the inductor and the two ends of the inductor will generate ringing phenomenon, which causes the inductor current to oscillate. In addition, if the boost-buck controller works in the PFM mode for a long time, the M2 and the M3 lower tubes are closed, the bootstrap capacitor cannot be charged, and the boost-buck controller may not work normally. Based on these two problems, the efficiency of the existing buck-boost controller is very low when the buck-boost controller works in the light load working mode.
To solve this problem, the present embodiment provides a method for improving the efficiency of the buck-boost controller, as shown in the above-mentioned S1-S3. The method will be further described with reference to the waveform diagrams of the inductor current in different operation modes as shown in fig. 5.
Fig. 5(a) shows an inductor current waveform when the four-switch-tube BUCK-boost controller enters a light-load operation mode in a BUCK cycle and operates in a charging state; fig. 5(b) shows the inductor current waveform when the four-switch-tube buck-BOOST controller enters the light-load operation mode during the BOOST cycle and operates in the charging state. In addition, no matter what cycle the buck-boost controller operates in, the control mode of the switching tube in the light load operation mode is the same in the charging state. Therefore, taking fig. 5(a) as an example to describe the control method of the switching tube in the charging state, after the inductor current is smaller than the first preset threshold, the PFM operation mode is entered, the second switching tube M2 and the fourth switching tube M4 are opened, the first switching tube M1 and the third switching tube M3 are closed at the same time, and the inductor current drops through the second switching tube M2 and the fourth switching tube M4. And performing zero-crossing detection on the inductive current, determining the time point when the inductive current is zero, closing the fourth switching tube M4 after the inductive current is detected to be zero, wherein the first switching tube M1, the third switching tube M3 and the fourth switching tube M4 are in a closed state, and the second switching tube M2 is in an open state. The timer is started, and current flows through the body diodes of the second switching tube M2 and the third switching tube M3. After the first time is timed, i.e. the inductive current returns to zero again, the third switch tube M3 is opened, and at this time, the second switch tube M2 and the third switch tube M3 are openedIn the open state, the first switch tube M1 and the fourth switch tube M4 are in the closed state, so that the bootstrap capacitor can be charged during the long-time no-switch period of the PFM operation mode. During the PFM working mode, the two ends of the inductor are pulled to the ground, the current on the inductor is close to zero, the buck-boost controller stops switching, the output voltage slowly drops, and the buck-boost controller judges the output voltage VoutAnd when the output voltage is less than the second preset threshold value, the PFM working mode is exited and the PWM working mode is entered.
Fig. 5(c) shows an inductor current waveform when the four-switch-tube BUCK-boost controller enters a light-load operation mode in a BUCK cycle and operates in a discharge state; fig. 5(d) shows the inductor current waveform when the four-switch-tube buck-BOOST controller enters the light-load operation mode in the BOOST cycle and operates in the discharging state. In addition, no matter what cycle the buck-boost controller operates in, the control mode of the switching tube in the light load operation mode is the same in the discharge state. Therefore, the control method of the switching tube in the discharging state will be described by taking fig. 5(c) as an example, and after the inductor current is smaller than the first preset threshold, the PFM operation mode is entered, the first switching tube M1 and the third switching tube M3 are opened, the second switching tube M2 and the fourth switching tube M4 are closed, and the inductor current drops through the first switching tube M1 and the third switching tube M3. And performing zero-crossing detection on the inductive current, determining the time point when the inductive current is zero, closing the first switching tube M1 after the inductive current is detected to be zero, wherein the third switching tube M3 is in an open state, and the first switching tube M1, the second switching tube M2 and the fourth switching tube M4 are in a closed state. The timer is started, and the current flows through the body diode of the third switch tube M3 and the second switch tube M2. After the first time is timed, namely the inductive current returns to zero again, the second switching tube M2 is turned on, at this time, the second switching tube M2 and the third switching tube M3 are in an open state, and the first switching tube M1 and the fourth switching tube M4 are in a closed state, so that the bootstrap capacitor can be charged during the long-time no-switch period of the PFM operating mode. During the PFM working mode, the two ends of the inductor are pulled to the ground, the current on the inductor is close to zero, the buck-boost controller stops switching, the output voltage slowly drops, and the buck-boost controller judges the output voltage VoutLess than the second preAnd after the threshold value is set, the PFM working mode is exited and the PWM working mode is entered.
Through foretell control mode, no matter be in charged state or under the discharge state, after getting into the light load mode of operation, the timesharing of four switch tubes of ingenious utilization is opened and is closed, optimize the mode of operation under the light load mode of operation, make the buck-boost controller stop the inductive current of switch during reduce to zero, prevent inductive current ringing phenomenon, and can charge for bootstrap capacitor during long-time not switch, prevent the unable problem of working of buck-boost controller, can show the efficiency that improves the buck-boost controller under the light load mode of operation.
As can be seen from fig. 4, in the PWM operating mode, when the buck-BOOST controller operates in the BOOST cycle, the inductor current is first decreased and then increased at the beginning of the cycle. Because the inductive current is zero in the PFM working mode, if the inductive current is zero, the PWM working mode is entered, and if the BOOST period is reached, the inductive current will first become a negative value, i.e. the current flows back to the input end, which affects the waveform of the inductive current.
In order to solve this problem, after exiting the light-load operation mode, the method of this embodiment further includes: judging the current period of the buck-boost controller; and if the boost-buck controller works in the boost period, shielding the switching tube control signal before the boost ramp is intersected with the boost loop control signal in the first boost period in the normal working mode.
Specifically, when the buck-boost controller is in a charging state, after exiting from the light-load working mode, the second switching tube and the third switching tube are closed, the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are all kept in a closed state, and after a boost slope is intersected with a boost loop control signal, the first switching tube and the third switching tube are opened. When the buck-boost controller is in a discharging state, after the buck-boost controller exits from a light-load working mode, the second switching tube and the third switching tube are closed, and the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are kept in a closed state; and after the boost ramp is intersected with the boost loop control signal, opening the second switch tube and the fourth switch tube.
The above method is further described below with reference to fig. 5:
referring to fig. 5(b), if the buck-boost controller operates in the boost cycle, the first cycle of the PWM operating mode shields the PWM signal when the boost ramp is not intersected with the boost loop control signal, that is, shields the conduction stages of the first switching tube M1 and the fourth switching tube M4, at this time, the first switching tube M1, the second switching tube M2, the third switching tube M3 and the fourth switching tube M4 are all turned off, so that a large reverse current is avoided, the two ends of SW1 and SW2 float, after the boost ramp is intersected with the boost loop control signal, the first switching tube M1 and the third switching tube M3 are turned on, and the inductive current is V £ VinThe rate of/L increases.
Referring to fig. 5(d), if the buck-boost controller operates in the boost cycle, the first cycle of the PWM operating mode shields the PWM signal when the boost ramp is not intersected with the boost loop control signal, that is, shields the conduction stages of the first switching tube M1 and the fourth switching tube M4, at this time, the first switching tube M1, the second switching tube M2, the third switching tube M3 and the fourth switching tube M4 are all turned off, so that a large reverse current is avoided, the two ends of SW1 and SW2 float, after the boost ramp is intersected with the boost loop control signal, the second switching tube M2 and the fourth switching tube M4 are turned on, and the inductor current is VinThe rate of/L increases.
As shown in fig. 6, it shows the output voltage waveform and the inductor current waveform of the buck-boost controller entering the PFM operation mode in the boost period in the charging state, where fig. 6(a) is the output voltage waveform, fig. 6(b) is the inductor current waveform, and fig. 6(c) is the operation mode conversion. Firstly, the buck-boost controller maintains the output voltage unchanged in a PWM (pulse width modulation) working mode, and enters a PFM (pulse frequency modulation) working mode after detecting that the inductive current is smaller than a first preset threshold value. Firstly, turning on M2 and M4, turning off M1 and M3 at the same time, enabling the inductive current to descend through M2 and M4, carrying out zero-crossing detection on the inductive current through a zero detection circuit, turning off M4 after detecting that the inductive current is zero, starting timing, and enabling the current to flow through body diodes of M2 and M3. After the first time is timed, the inductive current is close to zero, M2 and M3 are turned on, and M1 and M4 are turned off. Stopping in PFM operating mode sDuring the period of the switch, the output voltage can slowly drop, the boost-buck controller judges that the output voltage is smaller than a second preset threshold value, then the boost-buck controller exits the PFM mode, enters the PWM working mode, the first period entering the PWM working mode can shield PWM signals, namely shielding M1 and M4 conduction stages, at the moment, M1, M2, M3 and M4 are all closed, so that the occurrence of large reverse current is avoided, and then the inductive current is V-shapedinThe slope of/L rises. By the method, the efficiency of the buck-boost controller in the light-load working mode can be improved, the backward flow current generated when the light-load working mode is converted into the normal working mode can be avoided, and the waveform of the inductive current of the buck-boost controller can be optimized.
Example 2:
the present embodiment is configured to provide a system for improving efficiency of a buck-boost controller, as shown in fig. 7, the system includes:
the judging module M1 is used for judging the state of the buck-boost controller when the buck-boost controller enters the light-load working mode;
the charging state control module M2 is used for opening the second switching tube and the fourth switching tube and closing the first switching tube and the third switching tube if the buck-boost controller is in a charging state; the fourth switching tube is closed until the inductive current is zero; after delaying the first time, opening the third switch tube until the light-load working mode is exited; the first time is the time when the inductive current returns to zero again;
a discharge state control module M3, configured to open the first switch tube and the third switch tube, and close the second switch tube and the fourth switch tube if the buck-boost controller is in a discharge state; turning off the first switching tube until the inductive current is zero; and after delaying the first time, opening the second switch tube until the light-load working mode is exited.
Example 3:
this embodiment is used for providing an efficiency of increase buck-boost controller's equipment, includes:
a processor; and
a memory having computer-readable program instructions stored therein,
wherein the computer readable program instructions, when executed by the processor, perform the method of embodiment 1.
Example 4:
the present embodiment is directed to providing a computer readable storage medium, on which a computer program is stored, which when executed by a processor implements the steps of the method of embodiment 1.
Moreover, those skilled in the art will appreciate that aspects of the invention may be illustrated and described as embodied in several forms or conditions of patentability, including any new and useful combination of processes, machines, manufacture, or materials, or any new and useful improvement thereof. Accordingly, aspects of the present invention may be embodied entirely in hardware, entirely in software (including firmware, resident software, micro-code, etc.) or in a combination of hardware and software. The above hardware or software may be referred to as "data block," module, "" engine, "" unit, "" component, "or" system. Furthermore, aspects of the present invention may be represented as a computer product, including computer readable program code, embodied in one or more computer readable media.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. It is to be understood that the foregoing is illustrative of the present invention and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the appended claims. The invention is defined by the claims and their equivalents.
Claims (10)
1. A method of increasing the efficiency of a buck-boost controller, the method comprising:
judging the state of the buck-boost controller when the buck-boost controller enters a light-load working mode;
if the buck-boost controller is in a charging state, opening a second switching tube and a fourth switching tube, and closing a first switching tube and a third switching tube; the fourth switching tube is closed until the inductive current is zero; after delaying the first time, opening the third switch tube until the light-load working mode is exited; the first time is the time when the inductive current returns to zero again;
if the buck-boost controller is in a discharging state, opening the first switching tube and the third switching tube, and closing the second switching tube and the fourth switching tube; turning off the first switching tube until the inductive current is zero; and after delaying the first time, opening the second switch tube until the light-load working mode is exited.
2. The method of claim 1, wherein prior to determining the state of the buck-boost controller when entering the light-load operation mode, the method further comprises:
judging whether the inductive current is smaller than a first preset threshold value in real time in the working process of the buck-boost controller;
if so, the buck-boost controller enters the light load working mode;
if not, the buck-boost controller keeps a normal working mode.
3. The method of claim 2, wherein the normal operating mode is a PWM operating mode; when the buck-boost controller works in the PWM working mode, the buck-boost controller works in a boost period and a buck period alternately;
when the boost-buck controller works in the boost period, if the boost-buck controller is in a charging state, before a boost ramp intersects with a boost loop control signal, opening the first switch tube and the fourth switch tube, and closing the second switch tube and the third switch tube; after the boost ramp intersects with the boost loop control signal, opening the first switching tube and the third switching tube, and closing the second switching tube and the fourth switching tube; if the boost-buck controller is in a discharging state, before the boost ramp is intersected with the boost loop control signal, opening the first switch tube and the fourth switch tube, and closing the second switch tube and the third switch tube; after the boost ramp intersects with the boost loop control signal, opening the second switching tube and the fourth switching tube, and closing the first switching tube and the third switching tube;
when the buck-boost controller works in the buck period, if the buck-boost controller is in a charging state, before a buck slope is intersected with a buck loop control signal, opening the first switch tube and the fourth switch tube, and closing the second switch tube and the third switch tube; after the voltage reduction ramp is intersected with the voltage reduction loop control signal, the second switching tube and the fourth switching tube are opened, and the first switching tube and the third switching tube are closed; if the buck-boost controller is in a discharging state, before the buck ramp is intersected with the buck loop control signal, opening the first switch tube and the fourth switch tube, and closing the second switch tube and the third switch tube; after the voltage reduction ramp is intersected with the voltage reduction loop control signal, the first switching tube and the third switching tube are opened, and the second switching tube and the fourth switching tube are closed.
4. The method according to claim 1, wherein after the second switching tube and the fourth switching tube are opened, the first switching tube and the third switching tube are closed, or the first switching tube and the third switching tube are opened, and the second switching tube and the fourth switching tube are closed, the method further comprises performing zero-crossing detection on the inductive current, and determining a time point when the inductive current is zero.
5. The method of claim 1, wherein after delaying the first time and then opening the third switch tube or delaying the first time and then opening the second switch tube, the method further comprises:
judging whether the output voltage is smaller than a second preset threshold value or not;
if yes, exiting the light load working mode and entering a normal working mode;
if not, the light load working mode is kept.
6. The method of claim 1, wherein after said exiting said light-load mode of operation, said method further comprises:
judging the current period of the buck-boost controller;
and if the boost-buck controller works in a boost cycle, shielding the switching tube control signal before the boost ramp is intersected with the boost loop control signal in the first boost cycle in the normal working mode.
7. The method of claim 6, wherein masking the switching tube control signal before the boost ramp intersects the boost loop control signal in the first boost cycle in the normal operating mode comprises:
when the buck-boost controller is in a charging state, after the buck-boost controller exits the light-load working mode, the second switch tube and the third switch tube are closed, so that the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all in a closed state; after the boost ramp intersects the boost loop control signal, opening the first switching tube and the third switching tube;
when the buck-boost controller is in a discharging state, after the buck-boost controller exits the light-load working mode, the second switch tube and the third switch tube are closed, so that the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all in a closed state; after the boost ramp intersects the boost loop control signal, the second switching tube and the fourth switching tube are opened.
8. A system for improving the efficiency of a buck-boost controller, the system comprising:
the judging module is used for judging the state of the buck-boost controller when the buck-boost controller enters a light-load working mode;
the charging state control module is used for opening the second switching tube and the fourth switching tube and closing the first switching tube and the third switching tube if the buck-boost controller is in a charging state; the fourth switching tube is closed until the inductive current is zero; after delaying the first time, opening the third switch tube until the light-load working mode is exited; the first time is the time when the inductive current returns to zero again;
the discharge state control module is used for opening the first switching tube and the third switching tube and closing the second switching tube and the fourth switching tube if the buck-boost controller is in a discharge state; turning off the first switching tube until the inductive current is zero; and after delaying the first time, opening the second switch tube until the light-load working mode is exited.
9. An apparatus for improving the efficiency of a buck-boost controller, comprising:
a processor; and
a memory having computer-readable program instructions stored therein,
wherein the computer-readable program instructions, when executed by the processor, perform the method of any of claims 1-7.
10. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 7.
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