Bidirectional DC-DC conversion circuit, control method thereof and power supply

Abstract

The invention discloses a bidirectional direct current-direct current conversion circuit, a control method thereof and a power supply, and belongs to the technical field of electric energy conversion, the bidirectional direct current-direct current conversion circuit comprises n buck-boost conversion modules, m charge pump modules, n first switches and second switches, the first ends of the n buck-boost conversion modules are respectively connected with a first port to an nth port, and the second ends of the n buck-boost conversion modules are respectively connected with an n-th port; the second ends of the n buck-boost conversion modules are connected together; the first ends of the m charge pump modules are connected and then connected with the second ends of the n buck-boost conversion modules, the second ends of the m charge pump modules are connected and then connected with the first end of the battery, and the second end of the battery is grounded; two ends of the n buck-boost conversion modules are respectively connected with a first switch in parallel, two ends of the first charge pump module are connected with a second switch in parallel, and m and n are integers greater than or equal to 1. According to the invention, high conversion efficiency under high and low conversion ratios is realized through switching of different modes.

Description

Technical Field

[0001] The present invention relates to the technical field of power conversion, and particularly to a bidirectional DC-DC conversion circuit, a control method thereof, and a power supply. Background Art

[0002] In recent years, with the popularization of mobile electronic devices, the demand for mobile power supplies has been increasing day by day. Among them, the bidirectional DC-DC (Direct Current - Direct Current) conversion circuit is a topology commonly used in mobile power supplies. In the prior art, the bidirectional DC-DC conversion circuit usually adopts a single-stage architecture, such as a buck-boost conversion topology. When a high buck ratio or a high boost ratio needs to be achieved, the conversion efficiency of the buck-boost conversion topology is relatively low. In addition, for the case of a fixed conversion ratio or adjustable input / output voltage, the existing circuits are also difficult to meet the requirement of high efficiency.

[0003] Therefore, a new type of bidirectional DC-DC conversion circuit is needed. Summary of the Invention

[0004] The present invention aims to provide a bidirectional DC-DC conversion circuit, a control method thereof, and a power supply.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A bidirectional DC-DC conversion circuit includes n buck-boost conversion modules, m charge pump modules, n first switches and second switches. The first ends of the n buck-boost conversion modules are respectively connected to the first port to the nth port, and the second ends of the n buck-boost conversion modules are connected together; the first ends of the m charge pump modules are connected and then connected to the second ends of the n buck-boost conversion modules, and the second ends of the m charge pump modules are connected and then connected to the first end of the battery, and the second end of the battery is grounded; a first switch is connected in parallel at both ends of each of the n buck-boost conversion modules, and a second switch is connected in parallel at both ends of the first charge pump module. m and n are integers greater than or equal to 1.

[0007] The above-mentioned bidirectional DC-DC conversion circuit may further include n third switches, and the first ends of the n buck-boost conversion modules are respectively connected to the first port to the nth port through a third switch.

[0008] The above-mentioned bidirectional DC-DC conversion circuit may further include a battery protection module. The second ends of the m charge pump modules are connected to the first end of the battery protection module, and the second end of the battery protection module is connected to the first end of the battery.

[0009] The present invention also provides a control method for a bidirectional DC-DC conversion circuit, which is applied to the above-mentioned bidirectional DC-DC conversion circuit, including that when the ratio of the battery voltage to the input voltage or the ratio of the input voltage to the battery voltage is less than a first conversion ratio, the first switch is turned off and the second switch is closed, where the first conversion ratio is a value greater than 1.

[0010] Further, when the ratio of the battery voltage to the input voltage or the ratio of the input voltage to the battery voltage is greater than the first conversion ratio and the input voltage is fixed, the first switch and the second switch are turned off, where the first conversion ratio is a value greater than 1.

[0011] Further, when the ratio of the battery voltage to the input voltage or the ratio of the input voltage to the battery voltage is greater than the first conversion ratio and the input voltage is adjustable, the first switch is closed and the second switch is turned off, where the first conversion ratio is a value greater than 1.

[0012] Further, when the ratio of the battery voltage to the output voltage or the ratio of the output voltage to the battery voltage is less than a second conversion ratio, the first switch is turned off and the second switch is closed, where the second conversion ratio is a value greater than 1.

[0013] Further, when the ratio of the battery voltage to the output voltage or the ratio of the output voltage to the battery voltage is greater than the second conversion ratio and the output voltage is fixed, the first switch and the second switch are turned off, where the second conversion ratio is a value greater than 1.

[0014] Further, when the ratio of the battery voltage to the output voltage or the ratio of the output voltage to the battery voltage is greater than the first conversion ratio and the output voltage is adjustable, the first switch is closed and the second switch is turned off, where the second conversion ratio is a value greater than 1.

[0015] The present invention also provides a power supply, which includes the above-mentioned bidirectional DC-DC conversion circuit and also includes n ports, and the first ends of n buck-boost conversion modules are respectively connected to the first port to the nth port.

[0016] Beneficial effects: For a bidirectional DC-DC conversion circuit, its control method and power supply according to the present invention, in the case of a low conversion ratio, the charge pump module is bypassed; in the case of a high conversion ratio, if the input voltage or the output voltage is fixed, the buck-boost conversion module and the charge pump module are cascaded; in the case of a high conversion ratio, if the input voltage or the output voltage is adjustable, the buck-boost conversion module is bypassed, and high conversion efficiency under high and low conversion ratios is achieved through different mode switches. At the same time, it also needs to have the ability of parallel expansion, and multiple buck-boost modules or charge pump modules are connected in parallel to meet the requirements of high-power application scenarios.

[0017] To make the above features and advantages of the invention more obvious and understandable, specific embodiments are hereinafter given and detailed descriptions are made in conjunction with the accompanying drawings as follows. Brief Description of the Drawings

[0018] Figure 1 FIG. is a schematic circuit diagram of a first specific embodiment of a bidirectional DC-DC conversion circuit according to the present invention.

[0019] Figure 2 FIG. is a schematic circuit diagram of a second specific embodiment of a bidirectional DC-DC conversion circuit according to the present invention.

[0020] Figure 3 is the input-output curve of the charge pump module and the buck-boost conversion module. Detailed Embodiments

[0021] To make the objectives and technical solutions of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0022] Figure 1 FIG. is a schematic circuit diagram of a first specific embodiment of a bidirectional DC-DC conversion circuit according to the present invention. As Figure 1 shown, a bidirectional DC-DC conversion circuit according to the present invention includes a first buck-boost conversion module 11, a first charge pump module 21, a switch S11 and a switch S21. The first end of the first buck-boost conversion module 11 is connected to a port P1. The second end of the first buck-boost conversion module 11 is connected to the first end of the first charge pump module 21. The second end of the first charge pump module 21 is connected to the first end of a battery VB. The second end of the battery VB is grounded. The switch S11 is connected in parallel across the two ends of the first buck-boost conversion module 11. The switch S21 is connected in parallel across the two ends of the first charge pump module 21.

[0023] Further, the first buck-boost conversion module 11 and the first charge pump module 21 are bidirectional conversion circuits, which play a role in bidirectional energy transfer. Therefore, a bidirectional DC-DC conversion circuit according to the present invention can also achieve bidirectional energy transfer.

[0024] Further, the port P1 is connected to an external power supply or an external load. When the port P1 is connected to an external power supply, the external power supply charges the battery VB. When the port P1 is connected to an external load, the battery VB discharges to charge the external load.

[0025] More specifically, the first buck-boost conversion module 11 converts the voltage V bus into the voltage Vmb , or convert voltage V mb to voltage V bus .

[0026] More specifically, the first charge pump module 21 converts voltage V mb to voltage V bat , or convert voltage V bat to voltage V mb .

[0027] Optionally, a bidirectional DC-DC conversion circuit of the present invention may further include a switch S31. The first end of the first buck-boost conversion module 11 is connected to the port P1 through the switch S31. By controlling the on / off of the switch S31, the connection and disconnection between the port P1 and the battery VB can be controlled.

[0028] Optionally, a bidirectional DC-DC conversion circuit of the present invention may further include a battery protection module 31. The second end of the first charge pump module 21 is connected to the first end of the battery protection module 31, and the second end of the battery protection module 31 is connected to the first end of the battery VB. Wherein, the battery protection module 31 protects the battery VB.

[0029] Optionally, the port P1 may be a USB port or the like.

[0030] For application scenarios of high-power charging or discharging, multiple buck-boost conversion modules or multiple charge pump modules may be connected in parallel to meet the high-power requirements. In another specific embodiment, specifically refer to Figure 2 , a bidirectional DC-DC conversion circuit of the present invention includes n buck-boost conversion modules and m charge pump modules, specifically the first buck-boost conversion module 11 to the nth buck-boost conversion module 1n, and the first charge pump module 21 to the mth charge pump module 2m; the first ends of the first buck-boost conversion module 11 to the nth buck-boost conversion module 1n are respectively connected to the port P1 to the port Pn, and the second ends of the first buck-boost conversion module 11 to the nth buck-boost conversion module 1n are connected together; the first ends of the first charge pump module 21 to the mth charge pump module 2m are connected and then connected to the second ends of the first buck-boost conversion module 11 to the nth buck-boost conversion module 1n, and the second ends of the first charge pump module 21 to the mth charge pump module 2m are connected and then connected to the first end of the battery VB, and the second end of the battery VB is grounded; switches S11 to S1n are respectively connected in parallel at both ends of the first buck-boost conversion module 11 to the nth buck-boost conversion module 1n, and a switch S21 is connected in parallel at both ends of the first charge pump module 21. Wherein, m and n are integers greater than or equal to 1, and m and n may be equal or unequal.

[0031] Optionally, a bidirectional DC-DC conversion circuit of the present invention may further include switches S31 to S3n. The first ends of the first buck-boost conversion module 11 to the nth buck-boost conversion module 1n are respectively connected to ports P1 to Pn through switches S31 to S3n. By controlling the on / off of switches S31 to S3n, the connection and disconnection between each port and the battery VB can be controlled.

[0032] Optionally, a bidirectional DC-DC conversion circuit of the present invention may further include a battery protection module 31. The second ends of the first charge pump module 21 to the mth charge pump module 2m are connected to the first end of the battery protection module 31, and the second end of the battery protection module 31 is connected to the first end of the battery VB. Wherein, the battery protection module 31 protects the battery VB.

[0033] Further, ports P1 to Pn are connected to an external power supply or an external load. When ports P1 to Pn are connected to an external power supply, one or more external power supplies are controlled to charge the battery VB by controlling switches S31 to S3n; when ports P1 to Pn are connected to an external load, the battery VB is controlled to discharge to charge one or more external loads by controlling switches S31 to S3n.

[0034] In addition, the charge pump module and the buck-boost conversion module used in this application are both common circuit topologies in the prior art, and the design and application are simple.

[0035] Figure 3 The input and output curves of the charge pump module and the buck-boost conversion module are shown. Wherein, the x-axis is the voltage V bat , and the y-axis is the typical voltage V of the standard charging protocol bus . The red line marks the range of the voltage V when the charge pump module works in modes of 1:1, 2:1, and 4:1. Through this figure, it can be judged which mode the charge pump module is working in; the blue line is used to identify whether the working mode of the buck-boost conversion module is the buck mode or the boost mode. After selecting the mode of the charge pump module, if the blue line is above the red line, the buck-boost conversion module works in the boost mode, otherwise it works in the buck mode. mb The present invention also provides a control method for a bidirectional DC-DC conversion circuit, including the following steps.

[0036] When a bidirectional DC-DC conversion circuit of the present invention works in the charging mode, that is, when an external power supply charges the battery VB, the external power supply provides an input voltage V

[0037] , and the voltage of the battery VB is the voltage V in . B .

[0038] When in the case of a low conversion ratio, that is, the voltage VB The ratio with the input voltage V in or the input voltage V in and the voltage V B is less than the first conversion ratio k1, turn off the switch S11, close the switch S21, bypass the first charge pump module 21, and use the first buck-boost conversion module 11 to perform boost or buck conversion to convert the voltage V bus into the voltage V bat to supply power to the battery VB in a single stage. Among them, the first conversion ratio k1 is a value greater than 1.

[0039] Optionally, the value range of the first conversion ratio k1 is 2.0 to 2.2.

[0040] When in the high conversion ratio and the input voltage V in is fixed, that is, the ratio of the voltage V B to the input voltage V in or the input voltage V in and the voltage V B is greater than the first conversion ratio k1 and the input voltage V in is fixed, turn off the switch S11 and the switch S21, cascade the first buck-boost conversion module 11 and the first charge pump module 21, first perform buck or boost conversion through the first buck-boost conversion module 11 to convert the voltage V bus into the voltage V mb , and then pass through the first charge pump module 21 and adjust the ratio of the input voltage to the output voltage of the first charge pump module 21 to convert the voltage V mb into the voltage V bat to supply power to the battery VB in two stages.

[0041] When in the high conversion ratio and the input voltage V in is adjustable, that is, the ratio of the voltage V B to the input voltage V in or the input voltage V in and the voltage V B is greater than the first conversion ratio k1 and the input voltage V in is adjustable, for example, in the PPS mode, close the switch S11, turn off the switch S21, bypass the first buck-boost conversion module 11, use the first charge pump module 21 and adjust the ratio of the input voltage to the output voltage of the first charge pump module 21 to convert the voltage V bus into the voltage V bat to supply power to the battery VB in a single stage.

[0042] It can be seen that for the case of a low conversion ratio, bypassing the first charge pump module 21 and only supplying power through the first buck-boost conversion module 11 can reduce losses and achieve higher efficiency. For the case of a high conversion ratio, if the input voltage is fixed, the first buck-boost conversion module 11 and the first charge pump module 21 can be cascaded to supply power to achieve high conversion efficiency at a high conversion ratio; if the input voltage is adjustable, only supplying power through the first charge pump module 21 can reduce losses and also achieve high conversion efficiency at a high conversion ratio.

[0043] Furthermore, for the case of a fixed input voltage, the highest input voltage can be preferentially requested to optimize the charging efficiency to the greatest extent.

[0044] In a specific embodiment, assume that the voltage V B ranges from 2.8V to 4.1V.

[0045] When the ratio of the input voltage V in to the voltage V B is less than the first conversion ratio k1, for example, when the input voltage V in is less than 9V, turn off the switch S11, close the switch S21, bypass the first charge pump module 21, and use the first buck-boost conversion module 11 to step down the input voltage V in to the voltage V bat to supply single-stage power to the battery VB.

[0046] When the ratio of the input voltage V in to the voltage V B is greater than the first conversion ratio k1 and the input voltage V in is fixed, for example, when the input voltage V in is equal to 9V or 12V, turn off the switch S11 and the switch S21, cascade the first buck-boost conversion module 11 and the first charge pump module 21, first perform buck or boost conversion through the first buck-boost conversion module 11 to convert the voltage V bus to the voltage V mb , and then use the first charge pump module 21 to convert the voltage V mb to the voltage V bat to supply two-stage power to the battery VB. Among them, the ratio of the input voltage to the output voltage of the first charge pump module 21 can be set to 2:1.

[0047] When the ratio of the input voltage V in to the voltage V B is greater than the first conversion ratio k1 and the input voltage V in is fixed, for example, when the input voltage V inWhen it is equal to 15V or 20V, turn off switch S11 and switch S21. The first buck-boost conversion module 11 and the first charge pump module 21 are cascaded. First, perform buck or boost conversion through the first buck-boost conversion module 11 to convert the voltage V bus into voltage V mb , and then convert the voltage V mb to voltage V bat through the first charge pump module 21 to supply power to the battery VB in two stages. Among them, the ratio of the input voltage to the output voltage of the first charge pump module 21 can be set to 4:1.

[0048] When the input voltage V in and the voltage V B ratio is greater than the first conversion ratio k1 and the input voltage V in is adjustable. For example, when the voltage V B is required to be 3.6V, close switch S11, turn off switch S21, bypass the first buck-boost conversion module 11, use the first charge pump module 21 and adjust the ratio of the input voltage to the output voltage of the first charge pump module 21 to convert the voltage V bus into voltage V bat to supply power to the battery VB in a single stage. Among them, the ratio of the input voltage to the output voltage of the first charge pump module 21 can be set to 4:1, then the requested input voltage V in is 14.4V.

[0049] A control method for a bidirectional DC-DC conversion circuit of the present invention further includes the following steps.

[0050] When the bidirectional DC-DC conversion circuit of the present invention operates in the discharge mode, that is, when the battery VB discharges to charge an external load, provide the output voltage V o to the external load.

[0051] When in the case of a low conversion ratio, that is, the ratio of the output voltage V o and the voltage V B or the ratio of the voltage V B and the output voltage V o is less than the second conversion ratio k2, turn off switch S11, close switch S21, bypass the first charge pump module 21, and use the first buck-boost conversion module 11 to perform boost or buck conversion to convert the voltage V bat into voltage V bus , and the battery VB discharges to the external load in a single stage. Among them, the second conversion ratio k2 is a value greater than 1.

[0052] Optionally, the value range of the second conversion ratio k2 is 2.0 to 2.2.

[0053] When in a high conversion ratio and the output voltage Vo When fixed, i.e., the output voltage V o and the voltage V B ratio or the voltage V B and the output voltage V o ratio is greater than the second conversion ratio k2 and the output voltage V o is fixed, turn off the switches S11 and S21, cascade the first charge pump module 21 and the first buck - boost conversion module 11. First, pass through the first charge pump module 21 and adjust the ratio of the input voltage to the output voltage of the first charge pump module 21 to convert the voltage V bat into the voltage V mb ; then perform buck or boost conversion through the first buck - boost conversion module 11 to convert the voltage V mb into the voltage V bus , and the battery VB discharges in two - stages to the external load.

[0054] When in the high - conversion - ratio and the output voltage V o is adjustable, i.e., the output voltage V o and the voltage V B ratio or the voltage V B and the output voltage V o ratio is greater than the second conversion ratio k2 and the output voltage V o is adjustable, for example, in the PPS mode, close the switch S11, turn off the switch S21, bypass the first buck - boost conversion module 11, use the first charge pump module 21 and adjust the ratio of the input voltage to the output voltage of the first charge pump module 21 to convert the voltage V bat into the voltage V bus , and the battery VB discharges in a single - stage to the external load.

[0055] Thus, for the case of low conversion ratio, bypass the first charge pump module 21 and only discharge through the first buck - boost conversion module 11 to reduce losses and achieve higher efficiency. For the case of high conversion ratio, if the output voltage is fixed, the first buck - boost conversion module 11 and the first charge pump module 21 can be cascaded for discharging to achieve high conversion efficiency at high conversion ratio; if the output voltage is adjustable, only discharge through the first charge pump module 21 to reduce losses and also achieve high conversion efficiency at high conversion ratio.

[0056] In a specific embodiment, assume that the voltage V B range is 2.8V - 4.1V.

[0057] When the ratio of the output voltage V o and the voltage V B is less than the second conversion ratio k2, for example, the output voltage V oWhen it is 5V, turn off switch S11, close switch S21, bypass the first charge pump module 21, and use the first buck-boost conversion module 11 to boost the voltage V B to the output voltage V o , and perform single-stage discharge on the battery VB.

[0058] When the ratio of the output voltage V o to the voltage V B is greater than the second conversion ratio k2 and the output voltage V o is fixed, for example, when the output voltage V o is equal to 9V or 12V, turn off switch S11 and switch S21, first pass through the first charge pump module 21 and adjust the ratio of the input voltage to the output voltage of the first charge pump module 21 to convert the voltage V B into the voltage V mb ; then perform boost or buck conversion through the first buck-boost conversion module 11 to convert the voltage V mb into the voltage V bus , and perform two-stage discharge on the battery VB. Among them, the ratio of the input voltage to the output voltage of the first charge pump module 21 can be set to 2:1.

[0059] When the ratio of the output voltage V o to the voltage V B is greater than the second conversion ratio k2 and the output voltage V o is fixed, for example, when the output voltage V o is equal to 15V or 20V, turn off switch S11 and switch S21, first pass through the first charge pump module 21 and adjust the ratio of the input voltage to the output voltage of the first charge pump module 21 to convert the voltage V B into the voltage V mb ; then perform boost or buck conversion through the first buck-boost conversion module 11 to convert the voltage V mb into the voltage V bus , and perform two-stage discharge on the battery VB. Among them, the ratio of the input voltage to the output voltage of the first charge pump module 21 can be set to 4:1.

[0060] When the ratio of the output voltage V o to the voltage V B is greater than the second conversion ratio k2 and the output voltage V o is adjustable, for example, in the PPS mode, for example, when the voltage V B is 3.6V, close switch S1, turn off switch S2, bypass the first buck-boost conversion module 11, use the first charge pump module 21 and adjust the ratio of the input voltage to the output voltage of the first charge pump module 21 to convert the voltage V B into the voltage V bus, perform single-stage discharge for the battery VB. Among them, the ratio of the input voltage to the output voltage of the first charge pump module 21 can be set to 4:1, and the output voltage V o is 14.4V.

[0061] For the application scenarios of high-power charging or discharging, a control method for a bidirectional DC-DC conversion circuit according to the present invention further includes the following steps.

[0062] For the case of a low conversion ratio, turn off switches S11 to S1n, close switch S21, bypass the charge pump module, and only supply power or discharge through the buck-boost conversion module, which can reduce losses and achieve higher efficiency; at the same time, according to the power demand, control switches S31 to S3n to select an appropriate number of buck-boost conversion modules to meet the power demand. When supplying power, the battery can be charged through one or more ports via the corresponding buck-boost module, and when discharging, power can be supplied to the corresponding external load through one or more ports.

[0063] For the case of a high conversion ratio, if the input voltage or the output voltage is fixed, turn off switches S11 to S1n, turn off switch S21, and use the buck-boost conversion module and the charge pump module in cascade to supply power or discharge. At the same time, according to the power demand, control switches S31 to S3n to select an appropriate number of buck-boost conversion modules to meet the power demand. When supplying power, the battery can be charged through one or more ports via the corresponding buck-boost module and the charge pump module, and when discharging, power can be supplied to the corresponding external load through one or more ports to achieve high conversion efficiency at a high conversion ratio.

[0064] For the case of a high conversion ratio, if the input voltage or the output voltage is adjustable, close switches S11 to S1n, turn off switch S21, and only supply power or discharge through the charge pump module. At the same time, according to the power demand, control switches S31 to S3n. When supplying power, the battery can be charged through one or more ports via the charge pump module, and when discharging, power can be supplied to the corresponding external load through one or more ports, which can reduce losses and also achieve high conversion efficiency at a high conversion ratio.

[0065] The present invention also provides a power supply, which includes the above-mentioned bidirectional DC-DC conversion circuit and further includes n ports. The first ends of the n buck-boost conversion modules are respectively connected to the first port to the nth port.

[0066] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown sequentially as indicated by the arrows, these steps are not necessarily executed sequentially in the order indicated by the arrows. Unless there is a clear indication in this text, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, at least some of the steps in the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least some of the sub-steps or stages of other steps or other steps.

[0067] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field to which the present invention pertains may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to that defined by the appended patent application scope.

Claims

1. A bidirectional DC-DC conversion circuit, characterized in that: The invention comprises n buck-boost conversion modules, m charge pump modules, n first switches and second switches, wherein the first ends of the n buck-boost conversion modules are respectively connected to the first port to the nth port, and the second ends of the n buck-boost conversion modules are connected together; the first ends of the m charge pump modules are connected to the second ends of the n buck-boost conversion modules after being connected, and the second ends of the m charge pump modules are connected to the first end of a battery after being connected, and the second end of the battery is grounded; a first switch is respectively connected to the two ends of the n buck-boost conversion modules in parallel, and a second switch is connected to the two ends of the first charge pump module in parallel, and m and n are integers greater than or equal to 1.

2. A bidirectional DC-DC conversion circuit as claimed in claim 1, characterized in that: It may also include n third switches, and the first ends of the n buck-boost conversion modules are respectively connected to the first port to the nth port through a third switch.

3. A bidirectional DC-DC conversion circuit as claimed in claim 2, characterized in that: A battery protection module may also be included, wherein the second ends of the m charge pump modules are connected to the first end of the battery protection module, and the second end of the battery protection module is connected to the first end of the battery.

4. A control method for a bidirectional DC-DC conversion circuit, characterized in that: A bidirectional DC-DC conversion circuit as claimed in any one of claims 1 to 3, comprising: When the ratio of the battery voltage to the input voltage or the ratio of the input voltage to the battery voltage is less than the first conversion ratio, the first switch is turned off and the second switch is closed, wherein the first conversion ratio is a value greater than 1.

5. A control method for a bidirectional DC-DC converter circuit as claimed in claim 4, characterized in that: Also includes, When the ratio of the battery voltage to the input voltage or the ratio of the input voltage to the battery voltage is greater than a first conversion ratio and the input voltage is fixed, the first switch and the second switch are turned off, wherein the first conversion ratio is a value greater than 1.

6. A control method for a bidirectional DC-DC converter circuit as claimed in claim 5, characterized in that: It also includes closing the first switch and turning off the second switch when the ratio of the battery voltage to the input voltage or the ratio of the input voltage to the battery voltage is greater than the first conversion ratio and the input voltage is adjustable, wherein the first conversion ratio is a value greater than 1.

7. A control method for a bidirectional DC-DC converter circuit as claimed in claim 4, characterized in that: Also includes, When the ratio of the battery voltage to the output voltage or the ratio of the output voltage to the battery voltage is less than the second conversion ratio, the first switch is turned off and the second switch is closed, wherein the second conversion ratio is a value greater than 1.

8. A control method for a bidirectional DC-DC converter circuit as claimed in claim 7, characterized in that: It also includes turning off the first switch and the second switch when the ratio of the battery voltage to the output voltage or the ratio of the output voltage to the battery voltage is greater than the second conversion ratio and the output voltage is fixed, wherein the second conversion ratio is a value greater than 1.

9. A control method for a bidirectional DC-DC converter circuit as claimed in claim 8, characterized in that: It also includes closing the first switch and turning off the second switch when the ratio of the battery voltage to the output voltage or the ratio of the output voltage to the battery voltage is greater than the first conversion ratio and the output voltage is adjustable, wherein the second conversion ratio is a value greater than 1.

10. A power supply, characterized in that: It comprises a bidirectional DC-DC conversion circuit as described in any one of claims 1 to 3, and also comprises n ports, wherein the first ends of the n buck-boost conversion modules are respectively connected to the first port to the nth port.

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