Hybrid buck-boost switching power converter and control method

Abstract

The invention aims to provide a hybrid buck-boost switching power supply converter and a control method. The hybrid buck-boost switching power supply converter comprises an inductor, a first controllable group, a second controllable group and a load capacitor, wherein the first controllable group is arranged at the input end of the inductor; the second controllable group is arranged at the output end of the inductor; one end of the load capacitor is electrically connected with the output end of the second controllable group, and the other end of the load capacitor is grounded; each of the first controllable group and the second controllable group consists of at least two switching devices and is used for realizing voltage reduction or voltage boosting in the process of controlling the on-off of any switching device; and the inductive current is reduced all the time in the step-down or step-up process. According to the hybrid buck-boost switching power supply converter, the problem of discontinuous continuous output current can be solved while the inductive current can be reduced, and the inductive current can be reduced in the whole duty ratio range, so that the efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of switching power supply converters, and in particular to a hybrid buck-boost switching power supply converter and a control method thereof. Background Art

[0002] In recent years, buck-boost switching power converters have been widely used in mobile devices powered by lithium batteries, such as RF power amplifiers, battery chargers, and LED drivers. The input voltage range of lithium batteries is usually 2.7V-4.2V, and its output voltage will gradually decrease during use. Many applications of buck-boost switching power converters powered by lithium batteries set the target output voltage at around 3.4V. In order to provide the load with a target output voltage of 3.4V within the entire input voltage range of the lithium battery and extend the battery life, a switching power converter that can buck and boost is very necessary.

[0003] like Figure 1 The figure shows a conventional buck-boost converter (CBBC), whose voltage conversion ratio (CR) ranges from 0<CR<1 and 1<CR<+∞. In both modes, the inductor current (I L ) are both high, so an inductor with low DC resistance (DCR) is required to reduce conduction losses and a high saturation current to maintain sufficient inductance at full load. This requirement leads to the use of a larger inductor, which limits the power density of the converter. At the same time, the converter has discontinuous output current in the boost mode, resulting in large output voltage ripple and poor transient response due to the right half plane zero (RHP-zero) in the circuit structure in this mode.

[0004] In view of this, a hybrid buck-boost switching power converter that can reduce the inductor current in both the boost mode and the buck mode needs to be studied urgently. Summary of the invention

[0005] The object of the present invention is to provide a hybrid buck-boost switching power supply converter and a control method thereof, so as to at least solve one technical problem in the prior art.

[0006] The technical solution of the present invention is:

[0007] A hybrid buck-boost switching power converter, comprising:

[0008] inductance;

[0009] A first controllable group is arranged at the input end of the inductor;

[0010] A second controllable group is arranged at the output end of the inductor;

[0011] a load capacitor, one end of which is electrically connected to the output end of the second controllable group, and the other end of which is grounded;

[0012] The first controllable group and the second controllable group are both composed of at least two switch devices, and are used to achieve voltage reduction or voltage increase in the process of controlling the on and off of any of the switch devices; and always reduce the inductor current in the process of voltage reduction or voltage increase.

[0013] The first controllable group includes:

[0014] A first switch device, a drain electrically connected to an input power supply;

[0015] a fourth switch device, a drain of which is electrically connected to the input power supply, and a source of which is electrically connected to the source of the first switch device;

[0016] A sixth switch device has a drain electrically connected to the source of the fourth switch device, and the source of the sixth switch device is grounded.

[0017] A flying capacitor is provided between the source of the fourth switching device and the source of the first switching device.

[0018] The first switch device, the fourth switch device and the sixth switch device are N-channel MOSFETs.

[0019] The second controllable group includes:

[0020] A second switch device, a source of which is electrically connected to the output end of the inductor;

[0021] a third switch device, a drain of which is electrically connected to the source of the second switch device, and the source of the third switch device is grounded;

[0022] a fifth switching device, a source electrode of which is connected to a source electrode of a fourth switching device in the first controllable group;

[0023] The drain of the second switching device is electrically connected to the drain of the fifth switching device;

[0024] The non-grounded end of the load capacitor is electrically connected to the source of the second switch device.

[0025] The drain of the second switch device is electrically connected to a current detection device for measuring the output current.

[0026] The second switch device, the third switch device and the fifth switch device are N-channel MOSFETs.

[0027] A control method for a hybrid buck-boost switching power supply, based on the above hybrid buck-boost switching power supply converter, comprises:

[0028] In boost mode:

[0029] The duty cycle is D, the first switch device, the third switch device, and the fifth switch device are controlled to be turned on, and the second switch device, the fourth switch device, and the sixth switch device are turned off; the inductor L is charged to V IN , the voltage across the capacitor is discharged to V IN -V O ;

[0030] The duty cycle is 0.2, the first switch device, the second switch device, and the fifth switch device are controlled to be turned on, and the third switch device, the fourth switch device, and the sixth switch device are turned off; the inductor is discharged to V O -V IN , until the voltage across the capacitor is discharged to V IN -V O .

[0031] The duty cycle is 0.8-D, the second switch device and the fourth switch device are turned on, and the first switch device, the third switch device, the fifth switch device, and the sixth switch device are turned off; the inductor is discharged to 2V O -2V IN , the voltage across the capacitor is charged to V IN -V O .

[0032] In buck mode:

[0033] The duty cycle is D, the second and fourth switch devices of the control switch device are turned on, and the first, third, fifth and sixth switch devices are turned off; the inductor is charged to 2V IN -2V O ; The voltage across the capacitor is discharged to V IN -V O ;

[0034] The duty cycle is 0.2, the first switch device, the second switch device, and the fifth switch device are turned on, and the third switch device, the fourth switch device, and the sixth switch device are turned off; the inductor is charged to V IN -V O , the voltage across the capacitor is charged to V IN -V O ;

[0035] The duty cycle is 0.8-D, the third switch device and the sixth switch device are turned on, and the first switch device, the second switch device, the fourth switch device, and the fifth switch device are turned off; the inductor is discharged to 2VO -V IN , the voltage across the capacitor is discharged to V IN -V O .

[0036] In boost mode, the inductor volt-second balance law gives:

[0037] D*V IN =0.2*(V O -V IN )+(0.8-D)*(2V O -2V IN );

[0038] Get the conversion ratio:

[0039]

[0040] From the charge balance law of capacitor and load capacitor, we get:

[0041]

[0042] Where D is the duty cycle; I L is the inductor current; I O is the output current.

[0043] In buck mode, the inductor volt-second balance law gives:

[0044] D*(2V IN -2V O )+0.2*(V IN V O )=(0.8-D)*(2V O -V IN );

[0045] Get the conversion ratio:

[0046]

[0047] From the charge balance law of flying capacitor and load capacitor, we can get:

[0048]

[0049] Where D is the duty cycle; I L is the inductor current; I O is the output current.

[0050] The hybrid buck-boost switching power supply converter described in the present invention can reduce the inductor current and solve the problem of discontinuous continuous output current, and can reduce the inductor current within the entire duty cycle range, thereby improving efficiency; and the hybrid buck-boost switching power supply converter described in the present invention does not have a high-voltage node when in use, and can use ordinary processes, reducing the difficulty of production and area cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a circuit schematic diagram of a conventional buck-boost switching power converter;

[0052] Figure 2 A circuit schematic diagram of an existing buck-boost switching power converter;

[0053] Figure 3 A circuit schematic diagram of another existing buck-boost switching power converter;

[0054] Figure 4 The hybrid buck-boost switching power converter of the present invention;

[0055] Figure 5 for Figure 4 3 working state diagrams of the switching power converter in buck mode;

[0056] Figure 6 for Figure 4 3 working state diagrams of the switching power converter in boost mode;

[0057] Figure 7 for Figure 4 The switching power converter and Figure 1 , Figure 2 , Figure 3 The inductor current comparison diagram of the switching power converter shown;

[0058] Figure 8 for Figure 4 Efficiency simulation diagram of the switching power converter. DETAILED DESCRIPTION

[0059] The present application is further described below in conjunction with the accompanying drawings.

[0060] In addition to the traditional buck-boost switching power converter, there is also a circuit structure such as Figure 2 The buck-boost switching power converter shown in the figure realizes the reduction of the inductor current in the buck mode, thereby improving the circuit efficiency. In order to facilitate the correspondence with the accompanying drawings, the switching devices in this embodiment are directly represented by symbols, such as the first switching device S1, which is directly written as S1. Please note.

[0061] The structure has two working modes. In the buck mode, when the state is 1, the duty cycle is D, and the switching device S 10 , S 30 On, S 20 , S 40 Cut off, inductor L0 is charged to V IN -V O , until the voltage across the flying capacitor CF10 is discharged to V O ; In state 2, the duty cycle is 1-D, and the switching device S 20 On, S 10 , S 30 , S 40 Cut off, inductor L0 discharges to 2V O -V IN , the flying capacitor CF1 is charged to V O According to the volt-second balance law of inductor L0, the voltage conversion ratio of this structure can be obtained:

[0062]

[0063] By capacitor C F0 , C L0 The charge balance law gives:

[0064]

[0065] In boost mode, when state 1, the duty cycle is D, and the switching device S 40 On, S 10 , S 20 , S 30 Cut off, inductor L0 is charged to V IN Until the voltage across the flying capacitor CF1 is charged to V O ; In state 2, the duty cycle is 1-D, and the switching device S 10 , S 30 On, S 20 , S 40 Cut off, the inductor L discharges to V O -V IN , the flying capacitor CF10 is discharged to V O According to the volt-second balance law of inductor L0, the voltage conversion ratio of this structure can be obtained:

[0066]

[0067] By capacitor C F0 , C L0 The charge balance law gives:

[0068]

[0069] From equations ① and ③, it can be seen that the voltage conversion ratio range of this structure is 0.5<CR<1 and 1<CR<+∞, realizing buck and boost modes. Although this circuit can reduce the inductor current and improve circuit efficiency in buck mode compared to the traditional structure, the inductor current of this structure is still large in boost mode, resulting in large inductor parasitic resistance loss and switch conduction loss, and there is also discontinuous output current in boost mode, resulting in large output voltage ripple.

[0070] In the prior art, there is also a circuit structure such as Figure 3 The buck-boost switching power converter shown in the figure achieves a reduction in the inductor current in the entire voltage conversion ratio range, and at the same time the structure can obtain output current continuity, thereby reducing the output voltage ripple.

[0071] This structure has only one working mode. In the buck-boost mode, when the state is 1, the duty cycle is D, and the switch device S 100 , S 300 , S 500 , S 700 On, S 200 , S 400 , S 600 , S 800 Cut-off, inductance L 00 Charge to 3V IN -2V O , until the flying capacitor CF1 00 The voltage across the terminals is charged to V IN , capacitor C F200 The voltage across the two ends is discharged to 2V IN -V O ; In state 2, the duty cycle is 1-D, and the switching device S 200 , S 400 , S 600 , S 800 On, S 100 , S 300 , S 500 , S 700 Cut off, the inductor L discharges to V O , flying capacitor CF1 00 Discharge to V IN , capacitor C F200 Charge to 2V IN -V O . According to the inductance L 00 The voltage conversion ratio of this structure can be obtained by using the volt-second balance law.

[0072]

[0073] By capacitor C F00 , CL00 The charge balance law gives:

[0074]

[0075] From formula ⑤, we can see that the voltage conversion ratio range of this structure is 0<CR<1.5, realizing the buck and boost modes. Compared with the traditional structure, the structure proposed in this document can reduce the inductor current in the entire voltage conversion range, improve the circuit efficiency, and realize the continuous reduction of output current and output voltage ripple. However, this structure uses eight switching devices, which increases the chip manufacturing cost.

[0076] According to the following table 1, which is the voltage stress table of the switch device, Figure 3 The corresponding maximum voltage stress of the switching device is 3V IN -V O , the minimum voltage stress is V IN -V O Therefore, the structure needs to be manufactured using a high-voltage process, which will increase the cost and difficulty of chip manufacturing.

[0077]

[0078] go through Figure 1 , Figure 2 and Figure 3 From the analysis of the buck-boost inductive switching power supply converter, it can be seen that the traditional buck-boost inductive switching power supply converter has the advantage of a large conversion range, but it also has the problem of high conduction loss caused by large inductive current, discontinuous output current in the boost mode resulting in large output voltage ripple, and the right half plane zero RHP-zero in the circuit structure in this mode resulting in poor transient response. Figure 2 The buck-boost inductive switching power converter shown can reduce the inductor current in the buck mode, but the inductor current is still large in the boost mode, resulting in large inductor parasitic resistance losses and switch conduction losses, and the structure does not solve the problem of discontinuous output current in the boost mode. Figure 3 The buck-boost inductive switching power converter shown can reduce the inductor current and achieve continuous output current over the entire voltage conversion range, but the structure introduces high switching device voltage stress, which requires special high-voltage process manufacturing, increasing manufacturing cost and difficulty.

[0079] Based on this, in this embodiment, by adding a capacitor branch, the load is powered alternately through the inductor branch and the capacitor branch, which can achieve the reduction of the inductor current in the entire voltage conversion range while also solving the problem of discontinuous continuous output current. In addition, the circuit structure described in this embodiment does not require high-voltage production process, thereby reducing production costs.

[0080] Specific embodiment 1:

[0081] The present invention provides an embodiment:

[0082] like Figure 4 , a hybrid buck-boost switching power converter, comprising: an inductor L, a first controllable group, a second controllable group and a load capacitor C L ; Wherein, the first controllable group is arranged at the input end of the inductor L; the second controllable group is arranged at the output end of the inductor L; the load capacitor C L One end of the load capacitor C is electrically connected to the output end of the second controllable group, and the load capacitor C L The other end of the first controllable group and the second controllable group are each composed of at least two switching devices, which are used to achieve voltage reduction or voltage increase during the on-off process of controlling any of the switching devices; and the inductor current is always reduced during the voltage reduction or voltage increase process.

[0083] Specifically, the first controllable group includes: a first switch device S1, a fourth switch device S4, and a sixth switch device S6; wherein the drain of the first switch device S1 is electrically connected to the input power supply; the drain of the fourth switch device S4 is electrically connected to the input power supply, and the source of the fourth switch device S4 is electrically connected to the source of the first switch device S1; the drain of the sixth switch device S6 is electrically connected to the source of the fourth switch device S4, and the source of the sixth switch device S6 is grounded. A flying capacitor C is provided between the source of the fourth switch device S4 and the source of the first switch device S1. F1 The first switch device S1, the fourth switch device S4 and the sixth switch device S6 are N-channel MOSFETs.

[0084] The second controllable group includes: a second switch device S2, a third switch device S3, and a fifth switch device S5; wherein the source of the second switch device S2 is electrically connected to the output end of the inductor L; the drain of the third switch device S3 is electrically connected to the source of the second switch device S2, and the source of the third switch device S3 is grounded; the source of the fifth switch device S5 is connected to the source of the fourth switch device S4 in the first controllable group; the drain of the second switch device S2 is electrically connected to the drain of the fifth switch device S5; the load capacitor C L The non-grounded end is electrically connected to the source of the second switch device S2.

[0085] Preferably, the drain of the second switch device S2 is also electrically connected to a current detection device for measuring the output current. The second switch device S2, the third switch device S3 and the fifth switch device S5 are N-channel MOSFETs.

[0086] The working principle of the present invention is: Figure 5 , when this embodiment works in buck mode:

[0087] State 1: The second switch device S2 and the fourth switch device S4 of the control switch device are turned on, and the first switch device S1, the third switch device S3, the fifth switch device S5, and the sixth switch device S6 are turned off; at this time, the inductor current will flow through the second switch device S2, the fourth switch device S4 is turned on and the flying capacitor CF1, and the inductor L is charged to 2V IN -2V O At the same time, the voltage across the flying capacitor CF1 is discharged to V IN -V O .

[0088] State 2: Control the first switch device S1, the second switch device S2, and the fifth switch device S5 to be turned on, and the third switch device S3, the fourth switch device S4, and the sixth switch device S6 to be turned off; at this time, the inductor current will flow through the second switch device S2, and the inductor L will be charged to V IN -V O , until the flying capacitor C F1 The voltage across the terminals is charged to V IN -V O .

[0089] State 3, the duty cycle is 0.8-D, the third switch device S3 and the sixth switch device S6 are turned on, and the first switch device S1, the second switch device S2, the fourth switch device S4, and the fifth switch device S5 are turned off; at this time, the inductor current will flow through the third switch device S3, the sixth switch device S6 and the flying capacitor C F1 , the inductor L is discharged to 2V O -V IN , until the flying capacitor C F1 The voltage across the terminals is discharged to V IN -V O .

[0090] From the volt-second balance law of inductance L, we can get:

[0091] D*(2V IN -2V O )+0.2*(V IN -V O )=(0.8-D)*(2V O -V IN ) ⑦

[0092] The conversion ratio can be obtained from the above formula:

[0093]

[0094] By flying capacitor CF1 and C L The charge balance law gives:

[0095]

[0096] like Figure 6 , when this embodiment works in boost mode:

[0097] State 1, duty cycle is D, the first switch device S1, the third switch device S3, the fifth switch device S5 are turned on, and the second switch device S2, the fourth switch device S4, the sixth switch device S6 are turned off; at this time, the inductor current will flow through the third switch device S3, and the inductor L will be charged to V IN At the same time, the flying capacitor C F1 The voltage across the terminals is discharged to V IN -V O .

[0098] State 2, the duty cycle is 0.2, the first switch device S1, the second switch device S2, and the fifth switch device S5 are turned on, and the third switch device S3, the fourth switch device S4, and the sixth switch device S6 are turned off; at this time, the inductor current will flow through the second switch device S2, and the inductor L will discharge to V O -V IN , until the flying capacitor C F1 The voltage across the terminals is discharged to V IN -V O .

[0099] State 3, the duty cycle is 0.8-D, the second switch device S2 and the fourth switch device S4 are turned on, and the first switch device S1, the third switch device S3, the fifth switch device S5, and the sixth switch device S6 are turned off; at this time, the inductor current will flow through the second switch device S2, the fourth switch device S4 and the flying capacitor C F1 , the inductor L is discharged to 2V O -2V IN At the same time, the flying capacitor C F1 The voltage across the terminals is charged to V IN -V O .

[0100] From the volt-second balance law of inductance L, we can get:

[0101] D*V IN =0.2*(V O -V IN )+(0.8-D)*(2V O -2V IN ) ⑩

[0102] The conversion ratio can be obtained from the above formula:

[0103]

[0104] The flying capacitor CF1 and C L The charge balance law gives:

[0105]

[0106] Table 2 Voltage stress table of switch devices of the hybrid buck-boost switching power supply converter described in this embodiment

[0107] Switching Devices <![CDATA[S1]]> <![CDATA[S2]]> <![CDATA[S3]]> <![CDATA[S4]]> <![CDATA[S5]]> <![CDATA[S6]]> Voltage stress <![CDATA[V O ]]> <![CDATA[V O ]]> <![CDATA[V O ]]> <![CDATA[V IN ]]> <![CDATA[V O ]]> <![CDATA[V IN ]]>

[0108] This embodiment can solve the problem of discontinuous continuous output current while reducing the inductor current by adding a capacitor branch. Figure 2 ,and Figure 3 Compared with the prior art shown in FIG. 1 , the inductor current is reduced in the entire duty cycle range and the efficiency is improved. In addition, the circuit proposed in this embodiment has no high-voltage node and can use common processes, thereby reducing the manufacturing difficulty and area cost.

[0109] Verification stage:

[0110] By comparing formula ②, ④, ⑥, ⑨ and Compared with the traditional buck-boost switching power converter, Figure 2 The inductor current of the buck-boost switching power converter shown in FIG. 1 and the buck-boost switching power converter shown in FIG. 2 is as follows: Figure 7 shown in Figure 7 In the traditional Figure 1 Circuit diagram; the first circuit is Figure 2 The second circuit is Figure 3 circuit.

[0111] Depend on Figure 7 It can be seen that Figure 2 The inductor current of the buck-boost switching power converter shown in the figure is smaller than that of the conventional structure when the input voltage is higher than 3.4V, but the inductor current is the same as that of the conventional structure when the input voltage is lower than 3.4V; Figure 3 The buck-boost switching power supply converter shown in the embodiment can obtain a smaller inductor current in both the buck mode and the boost mode, which can effectively reduce the conduction loss and thus improve the efficiency. Figure 3 The circuit shown only requires six switching devices and one capacitor, and the switching devices can be manufactured using common processes, so it has higher efficiency and power density and can reduce manufacturing difficulty and cost.

[0112] The existing hybrid buck-boost switching power converter for lithium batteries can achieve a stable output of 3.4V for lithium batteries while meeting the requirements of reducing inductor current and continuous output current. However, its capacitor C F The voltage changes greatly from buck mode to boost or transition mode, causing C F The charging or discharging current is large, which will generate a large number of spikes on the chip's power nodes during mode switching, which will increase the risk of chip loss. Figure 8 This is the efficiency simulation diagram of this embodiment. It can be seen that the overall efficiency is above 93% in the entire input voltage range, and the peak efficiency reaches 97.6% when VIN=3.8V, IOUT=0.5A, indicating that the structure can effectively reduce the conduction loss by reducing the inductor current, thereby improving the overall efficiency.

[0113] In summary, the present invention proposes a hybrid buck-boost switching power converter that always reduces the inductor current, which can reduce the inductor current in the entire voltage conversion range, effectively reduce the conduction loss, and thus improve the efficiency. Moreover, the hybrid buck-boost switching power converter that always reduces the inductor current proposed by the present invention can be manufactured using common processes, reducing the difficulty of manufacturing and area cost.

[0114] The above disclosures are only several specific implementation scenarios of the present invention, but the present invention is not limited thereto, and any changes that can be thought of by a person skilled in the art should fall within the protection scope of the present invention. The above serial numbers of the present invention are only for description and do not represent the advantages and disadvantages of the implementation scenarios.

Claims

1. A hybrid buck-boost switching power converter, characterized in that: include: inductance; A first controllable group is arranged at the input end of the inductor; A second controllable group is arranged at the output end of the inductor; a load capacitor, one end of which is electrically connected to the output end of the second controllable group, and the other end of which is grounded; The first controllable group and the second controllable group are both composed of at least two switch devices, and are used to achieve voltage reduction or voltage increase in the process of controlling the on and off of any of the switch devices; and always reduce the inductor current in the process of voltage reduction or voltage increase.

2. The hybrid buck-boost switching power converter according to claim 1, characterized in that: The first controllable group includes: A first switch device, a drain electrically connected to an input power supply; a fourth switch device, a drain of which is electrically connected to the input power supply, and a source of which is electrically connected to the source of the first switch device; A sixth switch device has a drain electrically connected to the source of the fourth switch device, and the source of the sixth switch device is grounded.

3. The hybrid buck-boost switching power converter according to claim 2, characterized in that: A flying capacitor is provided between the source of the fourth switching device and the source of the first switching device.

4. The hybrid buck-boost switching power converter according to claim 2, characterized in that: The first switch device, the fourth switch device and the sixth switch device are N-channel MOSFETs.

5. The hybrid buck-boost switching power converter according to claim 1, characterized in that: The second controllable group includes: A second switch device, a source of which is electrically connected to the output end of the inductor; a third switch device, a drain of which is electrically connected to the source of the second switch device, and the source of the third switch device is grounded; a fifth switching device, a source electrode of which is connected to a source electrode of a fourth switching device in the first controllable group; The drain of the second switching device is electrically connected to the drain of the fifth switching device; The non-grounded end of the load capacitor is electrically connected to the source of the second switch device.

6. The hybrid buck-boost switching power converter according to claim 5, characterized in that: The drain of the second switch device is electrically connected to a current detection device for measuring the output current.

7. The hybrid buck-boost switching power converter according to claim 5, characterized in that: The second switch device, the third switch device and the fifth switch device are N-channel MOSFETs.

8. A control method for a hybrid buck-boost switching power supply, based on the hybrid buck-boost switching power supply converter according to any one of claims 1 to 7, characterized in that: include: In boost mode: The duty cycle is D, the first switch device, the third switch device, and the fifth switch device are controlled to be turned on, and the second switch device, the fourth switch device, and the sixth switch device are turned off; the inductor L is charged to V IN , the voltage across the flying capacitor is discharged to V IN -V O ; The duty cycle is 0.2, the first switch device, the second switch device, and the fifth switch device are controlled to be turned on, and the third switch device, the fourth switch device, and the sixth switch device are turned off; the inductor is discharged to V O -V IN , until the voltage across the flying capacitor is discharged to V IN -V O . The duty cycle is 0.8-D, the second switch device and the fourth switch device are turned on, and the first switch device, the third switch device, the fifth switch device, and the sixth switch device are turned off; the inductor is discharged to 2V O -2V IN , the voltage across the flying capacitor is charged to V IN -V O ; In buck mode: The duty cycle is D, the second and fourth switch devices of the control switch device are turned on, and the first, third, fifth and sixth switch devices are turned off; the inductor is charged to 2V IN -2V0; the voltage across the capacitor is discharged to V IN -V0; The duty cycle is 0.2, the first switch device, the second switch device, and the fifth switch device are turned on, and the third switch device, the fourth switch device, and the sixth switch device are turned off; the inductor is charged to V IN -V0, the voltage across the flying capacitor is charged to V IN -V0; The duty cycle is 0.8-D, the third switch device and the sixth switch device are turned on, and the first switch device, the second switch device, the fourth switch device, and the fifth switch device are turned off; the inductor is discharged to 2V0-V IN , the voltage across the flying capacitor is discharged to V IN -V 0。 9. The control method of the hybrid buck-boost switching power supply according to claim 8, characterized in that: In boost mode, the inductor volt-second balance law gives: D*V IN =0.2*(V O -V IN )+(0.8-D)*(2V O -2V IN ); Get the conversion ratio: From the charge balance law of capacitor and load capacitor, we get: Where D is the duty cycle; I L is the inductor current; I0 ​​is the output current.

10. The control method of the hybrid buck-boost switching power supply according to claim 8, characterized in that: In buck mode, the inductor volt-second balance law gives: D*(2V IN -2V O )+0.2*(V IN -V O )=(0.8-D)*(2V O -V IN ); Get the conversion ratio: From the charge balance law of flying capacitor and load capacitor, we can get: Where D is the duty cycle; I L is the inductor current; I O is the output current.

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