A bidirectional DC-DC converter circuit and power supply

Abstract

This utility model discloses a bidirectional DC-DC converter circuit and power supply, belonging to the field of power conversion technology. It includes n buck-boost converter modules, m charge pump modules, and n first and second switches. The first terminals of the n buck-boost converter modules are respectively connected to a first port to a nth port, and the second terminals of the n buck-boost converter modules are connected together. The first terminals of the m charge pump modules are connected to the second terminals of the n buck-boost converter modules, and the second terminals of the m charge pump modules are connected to the first terminal of a battery, with the second terminal of the battery grounded. A first switch is connected in parallel across each of the n buck-boost converter modules, and a second switch is connected in parallel across each of the first charge pump modules. m and n are integers greater than or equal to 1. This utility model provides a bidirectional DC-DC converter circuit and power supply that achieves high conversion efficiency at high and low conversion ratios through different mode switching.

Description

Technical Field

[0001] This utility model relates to the field of power conversion technology, and in particular to a bidirectional DC-DC converter circuit and power supply. Background Technology

[0002] In recent years, with the widespread adoption of mobile electronic devices, the demand for portable power banks has been increasing. Among these, bidirectional DC-DC converters are a commonly used topology in portable power banks. In existing technologies, bidirectional DC-DC converters typically employ a single-stage architecture, such as a buck-boost converter topology. However, when a high buck ratio or high boost ratio is required, the buck-boost converter topology exhibits relatively low conversion efficiency. Furthermore, existing circuits struggle to meet high efficiency requirements for fixed conversion ratios or adjustable input / output voltages.

[0003] Therefore, a new type of bidirectional DC-DC converter circuit is needed. Utility Model Content

[0004] The present invention aims to provide a bidirectional DC-DC converter circuit and power supply.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows:

[0006] A bidirectional DC-DC converter circuit includes n buck-boost converter modules, m charge pump modules, n first switches and second switches. The first terminals of the n buck-boost converter modules are respectively connected to a first port to a nth port, and the second terminals of the n buck-boost converter modules are connected together. The first terminals of the m charge pump modules are connected to the second terminals of the n buck-boost converter modules, and the second terminals of the m charge pump modules are connected to the first terminal of a battery, the second terminal of which is grounded. A first switch is connected in parallel across each of the n buck-boost converter modules, and a second switch is connected in parallel across each of the first charge pump modules. m and n are integers greater than or equal to 1.

[0007] The aforementioned bidirectional DC-DC converter circuit may further include n third switches, with the first terminals of the n buck-boost converter modules connected to the first port to the nth port via a third switch.

[0008] The aforementioned bidirectional DC-DC converter circuit may further include a battery protection module, wherein the second ends of 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] In one specific embodiment, when the ratio of battery voltage to input voltage or the ratio of input voltage to battery voltage is less than a 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.

[0010] In one specific embodiment, when the ratio of battery voltage to input voltage or the ratio of input voltage to 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.

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

[0012] In one specific embodiment, when the ratio of battery voltage to output voltage or the ratio of output voltage to 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.

[0013] In one specific embodiment, when the ratio of battery voltage to output voltage or the ratio of output voltage to 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, wherein the second conversion ratio is a value greater than 1.

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

[0015] This utility model also provides a power supply, including the above-mentioned bidirectional DC-DC converter circuit, and further including n ports, wherein the first ends of the n buck-boost converter modules are respectively connected to the first port to the nth port.

[0016] Beneficial effects: This utility model provides a bidirectional DC-DC converter circuit and power supply. In low conversion ratio scenarios, the charge pump module is bypassed; in high conversion ratio scenarios, if the input or output voltage is fixed, a buck-boost converter module is cascaded with the charge pump module; in high conversion ratio scenarios, if the input or output voltage is adjustable, the buck-boost converter module is bypassed, achieving high conversion efficiency at both high and low conversion ratios through different mode switching. Simultaneously, it also needs to have parallel expansion capabilities, using multiple buck-boost modules or charge pump modules connected in parallel to meet the needs of high-power applications.

[0017] To make the above-mentioned features and advantages of the utility model more apparent and understandable, specific embodiments are described below, and detailed descriptions are provided in conjunction with the accompanying drawings. Attached Figure Description

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

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

[0020] Figure 3 The input-output curves are for the charge pump module and the buck-boost converter module. Detailed Implementation

[0021] To make the objectives and technical solutions of the present utility model clearer, the technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present utility model. All other embodiments obtained by those skilled in the art based on the described embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0022] Figure 1 This is a circuit diagram of a first specific embodiment of a bidirectional DC-DC converter circuit according to this utility model. Figure 1 As shown, the present invention provides a bidirectional DC-DC converter circuit including a first buck-boost converter module 11, a first charge pump module 21, a switch S11, and a switch S21. The first terminal of the first buck-boost converter module 11 is connected to port P1, the second terminal of the first buck-boost converter module 11 is connected to the first terminal of the first charge pump module 21, the second terminal of the first charge pump module 21 is connected to the first terminal of the battery VB, and the second terminal of the battery VB is grounded. The switch S11 is connected in parallel across the two terminals of the first buck-boost converter module 11, and the switch S21 is connected in parallel across the two terminals of the first charge pump module 21.

[0023] Furthermore, the first buck-boost converter module 11 and the first charge pump module 21 are bidirectional conversion circuits, which play a role in bidirectional energy transfer. Therefore, the bidirectional DC-DC converter circuit of this utility model can also realize bidirectional energy transfer.

[0024] Furthermore, the port P1 is connected to an external power source or an external load. When the port P1 is connected to an external power source, the external power source charges the battery VB; when the port P1 is connected to an external load, the battery VB discharges and charges the external load.

[0025] More specifically, the first buck-boost converter module 11 converts voltage V bus Transformed into voltage Vmb Or the voltage V mb Transformed into voltage V bus .

[0026] More specifically, the first charge pump module 21 converts voltage V mb Transformed into voltage V bat Or the voltage V bat Transformed into voltage V mb .

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

[0028] Optionally, the bidirectional DC-DC converter circuit of this invention may further include a battery protection module 31, wherein 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. The battery protection module 31 provides protection for the battery VB.

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

[0030] The working principle of a bidirectional DC-DC converter circuit according to this invention will be further described below.

[0031] When the bidirectional DC-DC converter circuit of this invention operates in charging mode, i.e., when the external power supply is charging the battery VB, the external power supply provides the input voltage V. in The voltage of battery VB is voltage V. B .

[0032] When the conversion ratio is low, i.e., the voltage V B With input voltage V in The ratio or input voltage V in With voltage V B If the ratio is less than the first conversion ratio k1, switch S11 is turned off and switch S21 is closed, bypassing the first charge pump module 21. The first buck-boost converter module 11 is then used for boost or buck conversion to convert the voltage V. bus Transformed into voltage V bat This provides single-stage power to battery VB. The first conversion ratio k1 is a value greater than 1.

[0033] Optionally, the first transformation ratio k1 can be in the range of 2.0 to 2.2.

[0034] When the conversion ratio is high and the input voltage Vin Under fixed conditions, i.e., voltage V B With input voltage V in The ratio or input voltage V in With voltage V B The ratio is greater than the first conversion ratio k1 and the input voltage V in When fixed, switches S11 and S21 are turned off. The first buck-boost converter module 11 and the first charge pump module 21 are cascaded. The voltage V is first bucked or boosted through the first buck-boost converter module 11. bus Transformed into voltage V mb Then, by passing through the first charge pump module 21 and adjusting the ratio of its input voltage to its output voltage, the voltage V is... mb Transformed into voltage V bat This provides two-stage power supply for battery VB.

[0035] When the conversion ratio is high and the input voltage V in In the adjustable case, i.e., voltage V B With input voltage V in The ratio or input voltage V in With voltage V B The ratio is greater than the first conversion ratio k1 and the input voltage V in When adjustable, for example in PPS mode, switch S11 is closed and switch S21 is turned off, bypassing the first buck-boost converter module 11. The first charge pump module 21 is used, and the ratio of the input voltage to the output voltage of the first charge pump module 21 is adjusted to convert the voltage V... bus Transformed into voltage V bat This provides a single-stage power supply for battery VB.

[0036] Therefore, for low conversion ratios, bypassing the first charge pump module 21 and supplying power only through the first buck-boost converter module 11 can reduce losses and achieve higher efficiency. For high conversion ratios, if the input voltage is fixed, the first buck-boost converter module 11 and the first charge pump module 21 can be cascaded for power supply to achieve high conversion efficiency at high conversion ratios; if the input voltage is adjustable, supplying power only through the first charge pump module 21 can reduce losses and also achieve high conversion efficiency at high conversion ratios.

[0037] Furthermore, for a fixed input voltage, the highest input voltage can be requested first, which can optimize charging efficiency to the maximum extent.

[0038] In one specific embodiment, assume the voltage V B The voltage range is 2.8V-4.1V.

[0039] When the input voltage V inWith voltage V B The ratio is less than the first transformation ratio k1, for example, when the input voltage V in When the voltage is less than 9V, switch S11 is turned off and switch S21 is closed, bypassing the first charge pump module 21. The first buck-boost converter module 11 is then used to convert the input voltage V. in Step down to voltage V bat This provides a single-stage power supply for battery VB.

[0040] When the input voltage V in With voltage V B The ratio is greater than the first conversion ratio k1 and the input voltage V in When fixed, for example when the input voltage V in When the voltage is equal to 9V or 12V, switches S11 and S21 are turned off. The first buck-boost converter module 11 and the first charge pump module 21 are cascaded. The voltage is first bucked or boosted through the first buck-boost converter module 11 to convert the voltage V. bus Transformed into voltage V mb Then, the voltage V is converted by the first charge pump module 21. mb Transformed to voltage V bat This provides a two-stage power supply for the battery VB. The ratio of the input voltage to the output voltage of the first charge pump module 21 can be set to 2:1.

[0041] When the input voltage V in With voltage V B The ratio is greater than the first conversion ratio k1 and the input voltage V in When fixed, for example when the input voltage V in When the voltage is equal to 15V or 20V, switches S11 and S21 are turned off. The first buck-boost converter module 11 and the first charge pump module 21 are cascaded. The voltage is first bucked or boosted through the first buck-boost converter module 11 to convert the voltage V. bus Transformed into voltage V mb Then, the voltage V is converted by the first charge pump module 21. mb Transformed to voltage V bat This provides a two-stage power supply for battery VB. The input voltage to output voltage ratio of the first charge pump module 21 can be set to 4:1.

[0042] When the input voltage V in With voltage V B The ratio is greater than the first conversion ratio k1 and the input voltage V in When adjustable, for example when the voltage V B When the required voltage is 3.6V, close switch S11, turn off switch S21, bypass the first buck-boost converter 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 Transformed into voltage V bat This provides single-stage power to battery VB. The input voltage to output voltage ratio of the first charge pump module 21 can be set to 4:1, thus requesting an input voltage V. in It is 14.4V.

[0043] When the bidirectional DC-DC converter circuit of this invention operates in discharge mode, i.e., when the battery VB discharges to charge the external load, it provides the output voltage V. o To external load.

[0044] When the conversion ratio is low, i.e., the output voltage V o With voltage V B The ratio or voltage V B With output voltage V o If the ratio is less than the second conversion ratio k2, switch S11 is turned off and switch S21 is closed, bypassing the first charge pump module 21. The first buck-boost converter module 11 is then used for boost or buck conversion to convert the voltage V. bat Transformed into voltage V bus The battery VB discharges to an external load in a single stage. The second conversion ratio k2 is greater than 1.

[0045] Optionally, the second transformation ratio k2 can be in the range of 2.0 to 2.2.

[0046] When the conversion ratio is high and the output voltage V o Under fixed conditions, i.e., output voltage V o With voltage V B The ratio or voltage V B With output voltage V o The ratio is greater than the second conversion ratio k2 and the output voltage V o When fixed, switches S11 and S21 are turned off. The first charge pump module 21 and the first buck-boost converter module 11 are cascaded. First, the voltage V passes through the first charge pump module 21 and the ratio of its input voltage to its output voltage is adjusted to convert the voltage V. bat Transformed into voltage V mb Then, the voltage V is converted to voltage V by the first buck-boost converter module 11 through buck or boost conversion. mb Transformed into voltage V bus The battery VB discharges to the external load in two stages.

[0047] When the conversion ratio is high and the output voltage V o When adjustable, i.e., the output voltage V o With voltage V B The ratio or voltage V B With output voltage V oThe ratio is greater than the second conversion ratio k2 and the output voltage V o When adjustable, for example in PPS mode, switch S11 is closed and switch S21 is turned off, bypassing the first buck-boost converter module 11. The first charge pump module 21 is used, and the ratio of the input voltage to the output voltage of the first charge pump module 21 is adjusted to convert the voltage V... bat Transformed into voltage V bus The battery VB discharges to the external load in a single stage.

[0048] Therefore, for low conversion ratios, bypassing the first charge pump module 21 and discharging only through the first buck-boost converter module 11 can reduce losses and achieve higher efficiency. For high conversion ratios, if the output voltage is fixed, the first buck-boost converter module 11 and the first charge pump module 21 can be cascaded for discharging to achieve high conversion efficiency at high conversion ratios; if the output voltage is adjustable, discharging only through the first charge pump module 21 can reduce losses and also achieve high conversion efficiency at high conversion ratios.

[0049] In one specific embodiment, assume the voltage V B The voltage range is 2.8V-4.1V.

[0050] When the output voltage V o With voltage V B The ratio is less than the second conversion ratio k2, for example, the output voltage V o When the voltage is 5V, switch S11 is turned off and switch S21 is closed, bypassing the first charge pump module 21. The first buck-boost converter module 11 is then used to convert the voltage V. B Boost to output voltage V o The battery VB is discharged in a single stage.

[0051] When the output voltage V o With voltage V B The ratio is greater than the second conversion ratio k2 and the output voltage V o When fixed, for example when the output voltage V o When the voltage is equal to 9V or 12V, switches S11 and S21 are turned off. The voltage V is then passed through the first charge pump module 21, and the ratio of its input voltage to its output voltage is adjusted. B Transformed into voltage V mb Then, the voltage V is boosted or bucked through the first buck-boost converter module 11. mb Transformed into voltage V bus The battery VB is discharged in two stages. The ratio of the input voltage to the output voltage of the first charge pump module 21 can be set to 2:1.

[0052] When the output voltage V o With voltage VB The ratio is greater than the second conversion ratio k2 and the output voltage V o When fixed, for example when the output voltage V o When the voltage is equal to 15V or 20V, switch S11 and switch S21 are turned off. The voltage V is then passed through the first charge pump module 21, and the ratio of its input voltage to its output voltage is adjusted. B Transformed into voltage V mb Then, the voltage V is boosted or bucked through the first buck-boost converter module 11. mb Transformed into voltage V bus The battery VB is discharged in two stages. The ratio of the input voltage to the output voltage of the first charge pump module 21 can be set to 4:1.

[0053] When the output voltage V o With voltage V B The ratio is greater than the second conversion ratio k2 and the output voltage V o When adjustable, for example in PPS mode, for example when the voltage V B When the voltage is 3.6V, switch S1 is closed and switch S2 is closed, bypassing the first buck-boost converter module 11. The first charge pump module 21 is used, and the ratio of the input voltage to the output voltage of the first charge pump module 21 is adjusted to convert the voltage V... B Transformed into voltage V bus This allows for single-stage discharge of battery VB. The ratio of the input voltage to the output voltage of the first charge pump module 21 can be set to 4:1, resulting in an output voltage V. o It is 14.4V.

[0054] For high-power charging or discharging applications, multiple buck-boost converter modules or multiple charge pump modules can be connected in parallel to meet the high-power requirements. For another specific embodiment, please refer to [the relevant documentation / reference]. Figure 2This utility model discloses a bidirectional DC-DC converter circuit comprising n buck-boost converter modules and m charge pump modules, specifically, first buck-boost converter modules 11 to nth buck-boost converter modules 1n, and first charge pump modules 21 to mth charge pump modules 2m; the first terminals of the first buck-boost converter modules 11 to nth buck-boost converter modules 1n are respectively connected to ports P1 to Pn, and the second terminals of the first buck-boost converter modules 11 to nth buck-boost converter modules 1n are connected together; A charge pump module 21 is connected to the first terminal of the m-th charge pump module 2m, and then connected to the second terminals of the first buck-boost converter module 11 to the n-th buck-boost converter module 1n. The second terminals of the first charge pump module 21 to the m-th charge pump module 2m are then connected to the first terminal of the battery VB, and the second terminal of the battery VB is grounded. Switches S11 to S1n are connected in parallel across the two terminals of the first buck-boost converter module 11 to the n-th buck-boost converter module 1n, respectively. Switch S21 is connected in parallel across the two terminals of the first charge pump module 21. Here, m and n are integers greater than or equal to 1, and m and n can be equal or unequal.

[0055] Optionally, the bidirectional DC-DC converter circuit of this invention may further include switches S31 to S3n, with the first terminals of the first buck-boost converter module 11 to the nth buck-boost converter module 1n respectively connected to ports P1 to Pn via switches S31 to S3n. By controlling the on / off state of switches S31 to S3n, the connection and disconnection between each port and the battery VB can be controlled.

[0056] Optionally, the bidirectional DC-DC converter circuit of this utility model may further include a battery protection module 31, with the second ends of the first charge pump module 21 to the m-th charge pump module 2m connected to the first end of the battery protection module 31, and the second end of the battery protection module 31 connected to the first end of the battery VB. The battery protection module 31 provides protection for the battery VB.

[0057] Furthermore, ports P1 to Pn are connected to an external power source or an external load. When ports P1 to Pn are connected to an external power source, one or more external power sources charge the battery VB by controlling switches S31 to S3n. When ports P1 to Pn are connected to an external load, the battery VB discharges to charge one or more external loads by controlling switches S31 to S3n.

[0058] Furthermore, for cases with low conversion ratios, switching from S11 to S1n is turned off, and switching from S21 is closed to bypass the charge pump module. Power is supplied or discharged only through the buck-boost converter module, which can reduce losses and achieve higher efficiency. At the same time, according to the power requirements, switching from S31 to S3n can be controlled to select an appropriate number of buck-boost converter modules to meet the power requirements. When supplying power, the battery can be charged through one or more ports via the corresponding buck-boost module. When discharging, the corresponding external load can be supplied through one or more ports.

[0059] Furthermore, for high conversion ratio scenarios, if the input or output voltage is fixed, switches S11 to S1n and S21 are turned off. A buck-boost converter module and a charge pump module are cascaded for power supply or discharge. Simultaneously, switches S31 to S3n can be controlled to select an appropriate number of buck-boost converter modules to meet the power requirements. During power supply, the battery can be charged through one or more ports via the corresponding buck-boost module and charge pump module. During discharge, the corresponding external load can be powered through one or more ports to achieve high conversion efficiency under high conversion ratio.

[0060] Furthermore, for high conversion ratios, if the input or output voltage is adjustable, closing switches S11 to S1n and closing switch S21 allows power supply or discharge solely through the charge pump module. Simultaneously, switches S31 to S3n can be controlled according to power requirements. During power supply, the battery can be charged through one or more ports via the charge pump module, and during discharge, the corresponding external load can be powered through one or more ports. This reduces losses and achieves high conversion efficiency even with a high conversion ratio.

[0061] Furthermore, the charge pump module and buck-boost converter module used in this application are common circuit topologies in the prior art, and are simple to design and apply.

[0062] Figure 3 The input-output curves of the charge pump module and the buck-boost converter module are shown, where the x-axis represents the voltage V. bat The y-axis represents the typical voltage V of the standard charging protocol. bus The red line indicates the voltage V of the charge pump module when it operates in 1:1, 2:1, and 4:1 modes. mb The range of values ​​shown in the diagram indicates the operating mode of the charge pump module. The blue line indicates whether the buck-boost converter module operates in buck or boost mode. When the charge pump module mode is selected, if the blue line is above the red line, the buck-boost converter module operates in boost mode; otherwise, it operates in buck mode.

[0063] This utility model also provides a power supply, including the above-mentioned bidirectional DC-DC converter circuit, and further including n ports, wherein the first ends of the n buck-boost converter modules are respectively connected to the first port to the nth port.

[0064] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A bidirectional DC-DC converter circuit, characterized in that, It includes n buck-boost converter modules, m charge pump modules, n first switches and second switches. The first ends of the n buck-boost converter modules are respectively connected to the first port to the nth port, and the second ends of the n buck-boost converter modules are connected together. The first ends of the m charge pump modules are connected to the second ends of the n buck-boost converter modules, and the second ends of the m charge pump modules are connected to the first end of the battery, and the second end of the battery is grounded. A first switch is connected in parallel to each end of the n buck-boost converter modules, and a second switch is connected in parallel to each end of the first charge pump module. m and n are integers greater than or equal to 1.

2. The bidirectional DC-DC converter circuit as described in claim 1, characterized in that, It may also include n third switches, with the first terminals of the n buck-boost converter modules connected from the first port to the nth port via a third switch.

3. The bidirectional DC-DC converter circuit as described in claim 2, characterized in that, It may also include a battery protection module, wherein the second end of m charge pump modules is 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. The bidirectional DC-DC converter circuit as described in claim 1, characterized in that, When the ratio of battery voltage to input voltage or the ratio of input voltage to 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. The bidirectional DC-DC converter circuit as described in claim 1, characterized in that, When the ratio of battery voltage to input voltage or the ratio of input voltage to 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, wherein the first conversion ratio is a value greater than 1.

6. The bidirectional DC-DC converter circuit as described in claim 1, characterized in that, When the ratio of battery voltage to input voltage or the ratio of input voltage to 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, wherein the first conversion ratio is a value greater than 1.

7. The bidirectional DC-DC converter circuit as described in claim 1, characterized in that, When the ratio of battery voltage to output voltage or the ratio of output voltage to 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. The bidirectional DC-DC converter circuit as described in claim 1, characterized in that, When the ratio of battery voltage to output voltage or the ratio of output voltage to 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, wherein the second conversion ratio is a value greater than 1.

9. The bidirectional DC-DC converter circuit as described in claim 1, characterized in that, When the ratio of battery voltage to output voltage or the ratio of output voltage to 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, wherein the second conversion ratio is a value greater than 1.

10. A power supply, characterized in that, The circuit includes a bidirectional DC-DC converter as described in any one of claims 1-9, and further includes n ports, wherein the first ends of the n buck-boost converter modules are respectively connected to the first port to the nth port.

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