CN115882722A - Hybrid buck-boost DC-DC converter with flying capacitor - Google Patents
Hybrid buck-boost DC-DC converter with flying capacitor Download PDFInfo
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Abstract
The present disclosure provides a hybrid buck-boost dc-dc converter with flying capacitor, comprising: an input node connected to an input voltage source for receiving an input voltage; a power inductor, one end of which is connected to the input node and the other end of which is connected to the first switch node; one end of the flying capacitor is connected to the first switch node, and the other end of the flying capacitor is connected to the second switch node; one end of the first switch tube is connected to the second switch node, and the other end of the first switch tube is grounded; one end of the second switch tube is connected to the input node, and the other end of the second switch tube is connected to the second switch node; one end of the third switching tube is connected to the first switching node, the other end of the third switching tube is connected to the output node, and the output node is used for sending out output voltage; one end of the fourth switching tube is connected to the second switching node, and the other end of the fourth switching tube is connected to the output node; and the output end is connected with the output node and comprises an output capacitor and a load resistor which are arranged in parallel, and the output end generates load current under the action of output voltage.
Description
Technical Field
The present disclosure relates to the field of electronic devices and integrated circuits, and more particularly, to a hybrid buck-boost dc-dc converter with a flying capacitor.
Background
In battery powered mobile devices, the actual supply voltage required by the system circuitry may be higher or lower than the battery voltage. The most typical application scenario is: the power is supplied by the lithium battery, a fixed 3.3V is generated to supply power to the system, and the voltage of the battery is reduced from 5V to 2.5V along with the increase of the service time of the lithium battery. Therefore, the system requires a step-down dc-dc converter when the battery voltage is higher than 3.3V, and a step-up dc-dc converter when the battery voltage is lower than 3.3V. In this case, a buck-boost dc-dc converter with both boost and buck functions provides a good solution.
The traditional buck-boost converter is formed by cascading a traditional boost converter and a traditional buck converter, so that two power tubes are always connected in series with an inductor on a power path, and only one power tube is connected in series with the inductor for simple boost or buck converter, so that the conduction loss of the traditional buck-boost converter is very large, in order to improve the efficiency, the area of the power tube can only be increased to reduce the conduction resistance of the power tube, and the manufacturing cost of a chip is undoubtedly greatly increased.
In addition, the inductor of the conventional buck-boost converter is on the large current side in the boost mode or the buck mode, in other words, the inductor current is large, and in order to ensure the system efficiency, the inductor with a small DCR (direct current resistance) needs to be selected, and for the inductor, the smaller the DCR, the larger the size is, which not only increases the size of the chip, but also increases the cost.
Disclosure of Invention
Technical problem to be solved
In view of the above, the present disclosure provides a hybrid buck-boost dc-dc converter with flying capacitors to alleviate the technical problems of the prior art, such as the large size of the buck-boost converter, the high cost of improving efficiency, etc.
(II) technical scheme
The present disclosure provides a hybrid buck-boost dc-dc converter with flying capacitor, comprising: the power inductor comprises an input node, a power inductor, a flying capacitor, a first switching tube, a second switching tube, a third switching tube, a fourth switching tube and an output end. The input node is connected to an input voltage source and used for receiving an input voltage; one end of the power inductor is connected to the input node, and the other end of the power inductor is connected to the first switch node; one end of the flying capacitor is connected to the first switch node, and the other end of the flying capacitor is connected to the second switch node; one end of the first switch tube is connected to the second switch node, and the other end of the first switch tube is grounded; one end of the second switch tube is connected to the input node, and the other end of the second switch tube is connected to the second switch node; one end of the third switching tube is connected to the first switching node, the other end of the third switching tube is connected to an output node, and the output node is used for sending out an output voltage; one end of the fourth switching tube is connected to the second switching node, and the other end of the fourth switching tube is connected to the output node; the output end is connected with the output node and comprises an output capacitor and a load resistor which are arranged in parallel, and the output end generates load current under the action of output voltage.
According to an embodiment of the present disclosure, the converter operates in a buck mode when the input voltage is higher than the output voltage, and operates in a boost mode when the input voltage is less than the output voltage.
According to the embodiment of the disclosure, in the boost mode, the fourth switching tube is always disconnected, and the boost mode is divided into the first state and the second state according to the linkage state of the first switching tube, the second switching tube and the third switching tube.
According to the embodiment of the disclosure, in the first state, the first switch tube is turned on, and the second switch tube and the third switch tube are turned off; the voltage of the first switch node is smaller than the input voltage, the voltage difference between two ends of the power inductor is larger than 0, the power inductor is magnetized, and the current of the power inductor rises and charges the flying capacitor.
According to the embodiment of the disclosure, in the second state, the first switch tube is turned off, the second switch tube and the third switch tube are turned on, the voltage of the first switch node is the same as the voltage of the output node, the voltage of the second switch node is equal to the input voltage, the voltage of the first switch node is greater than the input voltage, the voltage difference between two ends of the power inductor is less than 0, the power inductor is demagnetized, the current of the power inductor is reduced, and the flying capacitor discharges to transmit charges to the output capacitor.
According to the embodiment of the disclosure, in the voltage reduction mode, the second switch tube is always disconnected, and the voltage reduction mode is divided into the third state and the fourth state according to the linkage state of the first switch tube, the third switch tube and the fourth switch tube.
According to the embodiment of the disclosure, in the third state, the first switching tube and the third switching tube are turned on, the fourth switching tube is turned off, the voltage of the first switching node is equal to the output voltage, the voltage of the second switching node is 0, the voltage of the first switching node is smaller than the input voltage, the voltage difference between two ends of the power inductor is larger than 0, the power inductor is magnetized, the current of the power inductor rises, the flying capacitor discharges, and charges flow to the output capacitor.
According to the embodiment of the disclosure, in the fourth state, the first switching tube and the third switching tube are disconnected, the fourth switching tube is connected, the voltage of the first switching node is twice the output voltage, the voltage of the second switching node is equal to the output voltage, the voltage of the first switching node is greater than the input voltage, the voltage difference between two ends of the power inductor is less than 0, the power inductor is demagnetized, the current of the power inductor is reduced, and the flying capacitor is charged.
According to an embodiment of the present disclosure, in boost mode, the power inductor current is equal to the load current; the first switch tube, the second switch tube, the third switch tube selects the switch tube whose maximum withstand voltage is the input voltage, the fourth switch tube selects the switch tube whose maximum withstand voltage is the output voltage.
According to the embodiment of the disclosure, in the step-down mode, the power inductor current is smaller than the load current, the first switch tube, the third switch tube and the fourth switch tube select the switch tube with the maximum withstand voltage value as the output voltage, and the second switch tube select the switch tube with the maximum withstand voltage value as the input voltage.
(III) advantageous effects
From the above technical solution, it can be seen that the hybrid buck-boost dc-dc converter with flying capacitor of the present disclosure has at least one or some of the following beneficial effects:
(1) The current on the inductor can be reduced in a voltage reduction mode and a voltage boosting mode, so that the high efficiency is ensured;
(2) On the premise of ensuring high efficiency, an inductor with larger DCR can be selected, and the size of the inductor can be reduced;
(3) The current on each switching tube is reduced while the inductive current is reduced, and the conduction loss of the switching tubes is greatly reduced;
(4) System for controlling a power supplyThe maximum voltage withstanding value of the middle switch tube is V IN The (5V) or the switch tube with similar voltage withstanding value does not need a high voltage withstanding tube, and the size of the switch tube can be reduced, the chip area can be saved, and the chip manufacturing cost can be reduced on the premise of ensuring the high efficiency of the system.
Drawings
FIG. 1a is a schematic diagram of a conventional buck-boost converter.
FIG. 1b is a schematic diagram of the conventional buck-boost converter shown in FIG. 1a in buck mode.
FIG. 1c is a schematic diagram of the conventional buck-boost converter shown in FIG. 1a in boost mode.
FIG. 2a is a schematic diagram of the main waveforms of the buck-boost converter shown in FIG. 1a in the buck mode.
FIG. 2b is a schematic diagram of the key waveforms of the conventional buck-boost converter shown in FIG. 1a in boost mode.
FIG. 3a is a schematic diagram of a prior art buck-boost converter with flying capacitor.
FIG. 3b is a schematic diagram of the buck-boost converter with fly capacitor in the prior art in the buck mode shown in FIG. 3 a.
FIG. 3c is a schematic diagram of the prior art buck-boost converter with flying capacitor of FIG. 3a in boost mode.
Fig. 4a is a schematic diagram of main waveforms of the circuit in the buck mode of the buck-boost converter with flying capacitor in the prior art shown in fig. 3 a.
Fig. 4b is a schematic diagram of the main waveforms of the circuit in the boost mode of the buck-boost converter with flying capacitor in the prior art shown in fig. 3 a.
Fig. 5 is a schematic diagram of a hybrid buck-boost dc-dc converter with flying capacitors according to an embodiment of the disclosure.
Fig. 6a is a schematic diagram of a first state of the hybrid buck-boost dc-dc converter with fly capacitors shown in fig. 5 in a boost mode.
Fig. 6b is a schematic diagram of a second state of the hybrid buck-boost dc-dc converter with fly capacitors shown in fig. 5 in a boost mode.
Fig. 7 is a schematic diagram of main waveforms of a circuit in a boost mode of a hybrid buck-boost dc-dc converter with a flying capacitor according to an embodiment of the disclosure.
Fig. 8a is a schematic diagram of a third state of the hybrid buck-boost dc-dc converter with flying capacitors shown in fig. 5 in buck mode.
Fig. 8b is a diagram illustrating a fourth state of the hybrid buck-boost dc-dc converter with flying capacitors shown in fig. 5 in buck mode.
Fig. 9 is a schematic diagram of main waveforms of a circuit in a buck mode of a hybrid buck-boost dc-dc converter with a flying capacitor according to an embodiment of the disclosure.
Fig. 10 is a schematic flowchart illustrating the operation of a hybrid buck-boost dc-dc converter with flying capacitors according to an embodiment of the disclosure.
Detailed Description
The utility model provides a mix buck-boost direct current-direct current converter with flying capacitor, is a totally new mix buck-boost direct current-direct current converter topological structure, and it is on the basis of traditional buck-boost converter, introduces 1 flying capacitor, can assist the inductance to charge to the output when boost mode and buck mode to this reduces the inductance current. And the current on each switching tube is reduced while the inductive current is reduced, the conduction loss of the switching tube is reduced, and the problem of voltage resistance is not introduced.
A conventional buck-boost converter is shown in FIG. 1a, and the converter structure includes 4 switching transistors S 1 ，S 2 ，S 3 ，S 4 And 1 power inductor L,1 output capacitor C OUT And a load resistor R OUT . The circuit has two working modes:
when the input voltage is greater than the output voltage (V) IN ＞V OUT ) When, as shown in fig. 1b, the circuit operates in buck mode, the operating principle is similar to that of a conventional buck converter, S 1 ，S 2 Two switches are alternately turned on, S 3 Normally on, switch node V sW1 At V IN And 0. Voltage conversion thereofRatio M (M = V) OUT /V IN ) The relation between the average current of the power inductor and the duty ratio D is as follows:
M＝D (1)
I L ＝I OUT (2)
wherein D is (0,1), M is (0,1), I L For power inductor current, I OUT For output current, or called load resistor R OUT The load current of (1).
When the input voltage is less than the output voltage (V) IN ＜V OUT ) When, as shown in fig. 1c, the circuit operates in boost mode, the operating principle is similar to that of a conventional boost converter, S 3 ，S 4 Two switching tubes are alternatively conducted, S 1 Normally on, second switch node V SW2 At V OUT And 0. Voltage conversion ratio M (M = V) OUT /V IN ) The relation between the average current of the inductor and the duty ratio D is as follows:
M＝1/(1-D) (3)
wherein D belongs to (0,1) and M belongs to (1, ∞).
The key waveforms of this circuit are shown in fig. 2a and 2 b. From the above analysis, it can be seen that, when the conventional buck-boost converter is in the buck or boost mode, each switch is normally turned on (S) 3 ，S 1 ) This greatly increases the conduction loss of the system, and to reduce the conduction loss, the switch must be oversized to achieve a lower on-resistance, which increases the cost of chip fabrication. Meanwhile, when the traditional buck-boost converter is in a buck or boost mode, the inductor current is very large, in order to reduce the loss on the inductor, the inductor with smaller DCR must be selected, and the smaller DCR is, the larger the inductor size is, so that the chip size is increased while the cost is increased.
In order to reduce the conduction loss, ISSCC2017 proposes a new topology, as shown in fig. 3a, the topology includes 4 switches, 1 power inductor L, and 1 flying capacitor C F An output capacitor C OUT And a load resistance R OUT 。
Similarly, when the input voltage is greater than the output voltage (V) IN ＞V OUT ) When the circuit is operating in buck mode, as shown in fig. 3b, in buck mode, just like a conventional buck converter, there are only two switches S 1 ，S 2 Alternately conducting, the switch node is at V IN And 0, S 3 ，S 4 The fly capacitor is always off, no charging and discharging process exists on the fly capacitor, and compared with a traditional buck-boost converter, 1 normally-on switch is omitted on a power path, so that the conduction loss of a circuit can be greatly reduced. In a depressurization mode:
M＝D (5)
I L ＝I OUT (6)
wherein D belongs to 0,1 and M belongs to 0,1. The key waveform diagram of the buck mode circuit is shown in fig. 4 a.
When the input voltage is less than the output voltage (V) IN ＜V OUT ) When the circuit is operating in boost mode, as shown in FIG. 3c, S in the circuit 1 ，S 3 ，S 4 Work, S 2 Is always off. In the DT-T time period, S 1 ，S 4 Charging the flying capacitor and switching the node V SW1 ＝V IN Second switch node voltage value V SW2 ＝V OUT ，V OUT ＜V IN Voltage difference V across power inductor SW1 -V SW2 Less than 0, demagnetizing the inductor, and making the voltage across the flying capacitor be V CF ＝V IN During the 0-DT period, S 1 ，S 4 Breaking, S 3 The voltage at two ends of the flying capacitor can not suddenly change, so that the voltage value V of the first switch node at the moment SW1 ＝V OUT +V CF ＝V IN +V OUT Second switch node voltage value V SW2 ＝V OUT ，V SW1 -V SW2 And if the voltage difference is more than 0, the voltage difference between the two ends of the inductor is positive, and the inductor is magnetized. Unfortunately, at this time S 1 Voltage stress of V IN +V OUT Thus S 1 A power tube with higher withstand voltage is required, which means chip area andan increase in manufacturing cost. In boost mode:
M＝1/(1-D) (7)
wherein D belongs to (0,1), M belongs to (1, ∞), and the average current of the inductor is larger than the load current. The key waveform diagram of the boost mode circuit is shown in fig. 4 b.
As can be seen from the above, the conventional buck-boost converter shown in fig. 1a requires 3 switching transistors in both the boost mode and the buck mode, and 1 switching transistor is always turned on, so that the conduction loss is large, and in order to achieve high efficiency, a switching transistor with a larger area must be used, which increases the chip area and increases the chip manufacturing cost. In addition, the inductor current is large in the boost mode and the buck mode, and in order to achieve high efficiency, the inductor with a smaller DCR must be used, and the inductor with a smaller DCR has a larger size, which increases the cost and the overall size of the chip. In the buck-boost converter with flying capacitor shown in fig. 3a, only two switches are operated in buck mode, and 3 switches are operated in boost mode, but one switch is not always conducted as in the conventional structure, so that the conduction loss of the switch is generally reduced compared with the conventional structure, but S is the conduction loss of the switch 1 A switching tube with high withstand voltage is required, which increases chip area and manufacturing cost, and decreases system efficiency.
In addition, the inductor current of the two structures is large in the boost mode and the buck mode, so that a large-size inductor is required, and meanwhile, the large inductor current also means that the conduction loss of the switching tube is large.
In view of the above problems, an object of the present invention is to provide a novel topology structure of a buck-boost converter, which can reduce the inductor current in both the boost mode and the buck mode, reduce the conduction loss of the switching tube and the loss of the inductor DCR, and simultaneously avoid the problem of voltage withstanding of the switching tube, thereby achieving high efficiency and greatly reducing the chip cost and size.
For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.
In an embodiment of the present disclosure, there is provided a hybrid buck-boost dc-dc converter having a flying capacitor, as shown in fig. 5, the hybrid buck-boost dc-dc converter having a flying capacitor, including:
an input node connected to an input voltage source for receiving an input voltage V IN ；
A power inductor L having one end connected to the input node and the other end connected to the first switching node V SW1 ；
Flying capacitor C F One end of which is connected to the first switching node V SW1 The other end of the flying capacitor is connected to a second switch node V SW2 ；
First switch tube S 1 One end of the first switch is connected to the second switch node V SW1 The other end is grounded;
a second switch tube S 2 One end connected to the input node and the other end connected to the second switching node V SW2 ；
Third switch tube S 3 One end of the first switch is connected to the first switch node V SW1 And the other end is connected to an output node for emitting an output voltage V OUT ；
Fourth switch tube S 4 One end of the first switch is connected to the second switch node V SW2 And the other end is connected to the output node;
an output end connected with the output node and including an output capacitor C arranged in parallel OUT And a load resistance R OUT And the output end generates load current under the action of the output voltage.
The converter operates in a buck mode when the input voltage is higher than the output voltage and in a boost mode when the input voltage is less than the output voltage. And during the boosting mode, the fourth switching tube is always disconnected, and the boosting mode is divided into a first state and a second state according to the linkage state of the first switching tube, the second switching tube and the third switching tube. And during the voltage reduction mode, the second switch tube is always disconnected, and the voltage reduction mode is divided into a third state and a fourth state according to the linkage state of the first switch tube, the third switch tube and the fourth switch tube.
In one embodiment of the present disclosure, when the input voltage is lower than the output voltage (V) IN ＜V OUT ) At this time, the circuit operates in a boost mode. In the boosting mode, the fourth switching tube S 4 Is always off, S 1 、S 2 And S 3 Alternately conducting, voltage V across flying capacitor CF ＝V OUT -V IN 。
More specifically, as shown in conjunction with FIGS. 6a, 7 and 10, during the first state (0-DT) period of boost mode, S 1 Conduction, S 2 And S 3 Disconnecting the first switch node voltage value V SW1 ＝V OUT -V IN Second switch node voltage value V SW2 ＝0，V SW1 Less than the input voltage V IN When the voltage difference between two ends of the inductor is greater than 0, the inductor is magnetized, the current of the inductor rises, and the flying capacitor is charged with + delta Q = I L DT, no charge is left from the input to the output capacitance during this time.
More specifically, as shown in conjunction with FIGS. 6b, 7 and 10, during the second state (DT-T) period, S 1 Breaking, S 2 And S 3 Conducting when the first switch node voltage value V SW1 ＝V OUT ，V SW2 ＝V IN ，V SW 1 is greater than input voltage V IN When the voltage difference between two ends of the inductor is less than 0, the inductor demagnetizes, the inductor current drops, and the flying capacitor discharges to the output capacitor C OUT And transferring the charge. The inductor is subjected to volt-second balance, and the following results can be obtained:
D(Y IN -(V OUT -Y IN ))＝(1-D)(V OUT -V IN ) (9)
wherein M is the voltage conversion ratio, D is the duty ratio, D belongs to (0,1), M belongs to (1,2), V IN Is the voltage value of the input voltage, V OUT Is the voltage value of the output voltage.
In boost mode, the waveform of the key signal is shown in FIG. 7, and the power inductor current I L ＝I OUT Lower than I in the conventional structure L ＝MI OUT (M > 1). In boost mode, the power inductor current is equal to the load current; first switch tube S 1 Second switch tube S 2 Third switch tube S 3 The switch tube with the maximum voltage withstanding value as the input voltage and the fourth switch tube S 4 The switching tube with the maximum voltage withstanding value as the output voltage is selected, for example, the range of the input voltage value is 2.5V-5V, and the range of the output voltage value is 3.3 +/-0.1V.
In one embodiment of the present disclosure, when the input voltage is higher than the output voltage (V) IN ＞V OUT ) When the circuit is in the step-down mode, S 2 Is always off, S 1 ，S 3 And S 4 Alternately conducting, voltage V across flying capacitor CF ＝V OUT 。
More specifically, as shown in conjunction with fig. 8a, 9 and 10, during the third state (0-DT) period of the buck mode, S 1 ，S 3 Conduction, S 4 Off, at which time switch node V SW1 ＝V OUT ，V SW2 ＝0，V SW1 Less than the input voltage V IN When the voltage difference between the two ends of the inductor is greater than 0, the inductor is magnetized, the current of the inductor rises, the flying capacitor discharges at the moment, and the charges flow to the output capacitor Cout.
More specifically, as shown in conjunction with fig. 8b, 9 and 10, during the fourth state (DT-T) period, S 1 ，S 3 Breaking, S 4 Is conducted at the time of switching node V SW1 ＝2V OUT ，V SW2 ＝V OUT ，V SW1 Greater than the input voltage V IN When the voltage difference between two ends of the inductor is less than 0, the inductor demagnetizes, the inductor current decreases, and the flying capacitor is charged at the moment, + delta Q = I L And (4) DT. The inductance is balanced in volt-second, and the following can be obtained:
D(V IN -V OUT )＝(1-D)(2V OUT -V IN ) (11)
wherein M is the voltage conversion ratio, D is the duty ratio, D belongs to (0,1), M belongs to (0.5,1), V IN Is the voltage value of the input voltage, V OUT Is the voltage value of the output voltage.
In the buck mode, the main signal waveform of the circuit is shown in FIG. 9, the inductor current I L ＝MI OUT (M < 1), lower than I in the conventional structure L ＝I OUT . In the step-down mode, the power inductor current is smaller than the load current, and the first switch tube S 1 A third switching tube S 3 Fourth switch tube S 4 A switch tube with the maximum voltage withstanding value as the output voltage, a second switch tube S 2 The switching tube with the maximum voltage withstanding value as the input voltage is selected, for example, the range of the input voltage value is 2.5V-5V, and the range of the output voltage value is 3.3 +/-0.1V.
So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It is to be understood that the implementations not shown or described in the drawings or in the text of this specification are in a form known to those skilled in the art and are not described in detail. Further, the above definitions of the various elements and methods are not limited to the various specific structures, shapes or arrangements of parts mentioned in the examples, which may be easily modified or substituted by those of ordinary skill in the art.
From the above description, those skilled in the art should have clear recognition of the hybrid buck-boost dc-dc converter with flying capacitor of the present disclosure.
In summary, the present disclosure provides a hybrid buck-boost dc-dc converter with flying capacitors, which introduces 1 flying capacitor on the basis of 4 power transistors and 1 power transistor in the conventional structure, so that the conduction loss of the power transistor is greatly reduced while the inductor current is reduced under all working conditions, the chip area and the inductor size can be greatly reduced on the premise of ensuring the high efficiency of the system, and the chip cost and the size can be reduced.
It is also noted that the above provides many different embodiments for the disclosure. These examples are intended to illustrate the technical content of the present disclosure, and are not intended to limit the scope of the claims of the present disclosure. Features of one embodiment may be applied to other embodiments by appropriate modification, substitution, combination, or separation.
It should be noted that, unless otherwise specified herein, the inclusion of "a" or "an" element is not limited to inclusion of a single such element, but may include one or more such elements.
Moreover, unless otherwise specified, the terms "first," "second," and the like, are used solely to distinguish one element from another, and do not denote a step, level, order of execution, or order of manufacture, unless otherwise indicated. A "first" element and a "second" element may be present together in the same component or separately in different components. The presence of an element having a higher ordinal number does not necessarily indicate the presence of another element having a lower ordinal number.
In this context, unless otherwise specified, the term "or" and/or "characteristic" means the presence of a, alone or in combination with B; by the features A and (and) or "and" feature B, it is meant that A and B are present simultaneously; the terms "comprising," "including," "having," "containing," and "containing" are intended to be inclusive and not limiting.
Moreover, the terms "upper," "lower," "left," "right," "front," "rear," or "between," and the like, as used herein, are used merely to describe relative positions of various elements and are to be construed to include translational, rotational, or mirror-image situations. Further, in this document, unless specifically stated otherwise, "an element on" or the like does not necessarily mean that the element contacts another element.
In addition, unless steps are specifically described or must occur in sequence, the order of the steps is not limited to that listed above and may be changed or rearranged as desired by the desired design. The embodiments described above may be mixed and matched with each other or with other embodiments based on design and reliability considerations, i.e., technical features in different embodiments may be freely combined to form further embodiments.
The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.
Claims (10)
1. A hybrid buck-boost dc-dc converter with flying capacitor, comprising:
an input node connected to an input voltage source for receiving an input voltage;
a power inductor, one end of which is connected to the input node and the other end of which is connected to the first switch node;
one end of the flying capacitor is connected to the first switch node, and the other end of the flying capacitor is connected to the second switch node;
one end of the first switch tube is connected to the second switch node, and the other end of the first switch tube is grounded;
one end of the second switch tube is connected to the input node, and the other end of the second switch tube is connected to the second switch node;
one end of the third switching tube is connected to the first switching node, the other end of the third switching tube is connected to an output node, and the output node is used for sending out output voltage;
one end of the fourth switching tube is connected to the second switching node, and the other end of the fourth switching tube is connected to the output node;
the output end is connected with the output node and comprises an output capacitor and a load resistor which are arranged in parallel, and the output end generates load current under the action of output voltage.
2. The hybrid buck-boost dc-dc converter with flying capacitor of claim 1, the converter operating in buck mode when the input voltage is higher than the output voltage and in boost mode when the input voltage is less than the output voltage.
3. The hybrid buck-boost dc-dc converter with flying capacitor of claim 2, wherein in the boost mode, the fourth switching tube is always turned off, and the boost mode is divided into the first state and the second state according to the linkage state of the first switching tube, the second switching tube and the third switching tube.
4. The hybrid buck-boost dc-dc converter with flying capacitor of claim 3, wherein in the first state, the first switch tube is turned on, and the second switch tube and the third switch tube are turned off; the voltage of the first switch node is smaller than the input voltage, the voltage difference between two ends of the power inductor is larger than 0, the power inductor is magnetized, and the current of the power inductor rises and charges the flying capacitor.
5. The hybrid buck-boost dc-dc converter as claimed in claim 3, wherein in the second state, the first switch is turned off, the second switch and the third switch are turned on, the voltage at the first switch node is the same as the voltage at the output node, the voltage at the second switch node is equal to the input voltage, the voltage at the first switch node is greater than the input voltage, the voltage difference across the power inductor is less than 0, the power inductor is demagnetized, the current at the power inductor is decreased, and the flying capacitor discharges to transfer charge to the output capacitor.
6. The hybrid buck-boost dc-dc converter with flying capacitor of claim 2, wherein in the buck mode, the second switch is always off, and the buck mode is divided into a third state and a fourth state according to the linkage status of the first switch and the third and fourth switches.
7. The hybrid buck-boost dc-dc converter with flying capacitor of claim 6, wherein in the third state, the first switching transistor and the third switching transistor are turned on, the fourth switching transistor is turned off, the voltage at the first switching node is equal to the output voltage, the voltage at the second switching node is 0, the voltage at the first switching node is lower than the input voltage, the voltage difference across the power inductor is greater than 0, the power inductor is magnetized, the power inductor current rises, the flying capacitor discharges, and the charge flows to the output capacitor.
8. The hybrid buck-boost dc-dc converter of claim 6 having a flying capacitor, wherein in a fourth state, the first switching transistor and the third switching transistor are off, the fourth switching transistor is on, the voltage at the first switching node is twice the output voltage, the voltage at the second switching node is equal to the output voltage, the voltage at the first switching node is greater than the input voltage, the voltage difference across the power inductor is less than 0, the power inductor is demagnetized, the power inductor current is decreased, and the flying capacitor is charged.
9. A hybrid buck-boost dc-dc converter having a flying capacitor as claimed in any one of claims 2 to 8, the power inductor current being equal to the load current in boost mode; the first switch tube, the second switch tube, the third switch tube selects the switch tube whose maximum withstand voltage is the input voltage, the fourth switch tube selects the switch tube whose maximum withstand voltage is the output voltage.
10. The hybrid buck-boost dc-dc converter according to any of claims 2 to 8, wherein in buck mode, the power inductor current is less than the load current, the first switch transistor, the third switch transistor, the fourth switch transistor are selected to have the maximum voltage endurance as the output voltage, and the second switch transistor is selected to have the maximum voltage endurance as the input voltage.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310070833.4A CN115882722A (en) | 2023-01-13 | 2023-01-13 | Hybrid buck-boost DC-DC converter with flying capacitor |
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| CN202310070833.4A CN115882722A (en) | 2023-01-13 | 2023-01-13 | Hybrid buck-boost DC-DC converter with flying capacitor |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116131602A (en) * | 2023-04-20 | 2023-05-16 | 合肥乘翎微电子有限公司 | DC-DC conversion circuit, converter and control method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116131602A (en) * | 2023-04-20 | 2023-05-16 | 合肥乘翎微电子有限公司 | DC-DC conversion circuit, converter and control method thereof |
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