A dc source based uninterruptible power supply topology and method

Abstract

The application provides a DC source-based uninterrupted power supply topology and method, which comprises a power supply gun, a charging gun, a lithium ion battery pack, a first diode, a DC bus, a load, a first on-off component, a second on-off component and a third on-off component; the charging gun and the power supply gun are connected with an external DC source; the DC bus is connected with the load; the power supply gun is connected with the DC bus; one end of the lithium ion battery pack is connected with the charging gun, and the other end is connected with the anode of the first diode; the cathode of the first diode is connected with the DC bus; the anode of the second diode is connected with the third on-off component; and the cathode is connected with the DC bus. Compared with the prior art, the technical scheme of the application can solve the technical problem that the lithium ion battery pack is prone to thermal runaway when charging and discharging simultaneously in the uninterrupted power supply scenario.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage power supply, and in particular to an uninterrupted power supply topology based on a DC source and an uninterrupted power supply method. BACKGROUND

[0002] With the rapid development of social economy, more and more application scenarios need to have uninterrupted power supply capability, such as hospital, fire fighting and other application scenarios. Lithium ion batteries have the advantages of high energy density, high specific energy, high power density, long cycle life, high operating voltage and low self-discharge rate, and are increasingly favored by people. However, lithium ion batteries are a closed system in thermodynamics, and once misused, such as charging while discharging, the battery may experience thermal runaway, causing fire or even explosion. Therefore, in the scenario of uninterrupted power supply, in order to avoid the lithium ion battery pack from charging while discharging, a power supply topology needs to be designed, which can use other DC power supply equipment to supply power to the load when the battery pack is charging, so as to cooperate with the lithium battery pack to realize uninterrupted power supply, but there is currently no topology that can realize uninterrupted power supply. SUMMARY

[0003] In order to solve one of the problems in the prior art, the present application provides an uninterrupted power supply topology based on a DC source and an uninterrupted power supply method.

[0004] According to one aspect of the present application, an uninterrupted power supply topology based on a DC source is provided, which includes a power supply gun, a charging gun, a lithium ion battery pack, a first diode, a DC bus, a load, a first on-off component, a second on-off component and a third on-off component. The charging gun and the power supply gun are connected with an external DC source, the DC bus is connected with the load, the power supply gun is connected with the DC bus, one end of the lithium ion battery pack is connected with the charging gun, the other end is connected with the anode of the first diode, the cathode of the first diode is connected with the DC bus, the anode of the second diode is connected with the third on-off component, and the cathode is connected with the DC bus.

[0005] The first on-off component is arranged between the power supply gun and the DC bus, and is used to close to supply power to the load by the power supply gun using the external DC source and to open to stop power supply. The second on-off component is arranged between the charging gun and the lithium ion battery pack, and is used to close to charge the lithium ion battery by the charging gun using the external DC source and to open to stop charging. The third on-off component is arranged between the lithium ion battery pack and the diode, and is used to close to supply power to the load using the lithium ion battery pack and to open to stop power supply.

[0006] The charging gun is used to cooperate with the first, second and third on-off components to charge the lithium ion battery when the lithium ion battery pack is in a power shortage state, the power gun is used to cooperate with the first, second and third on-off components to supply power to the load instead of the lithium ion battery pack when the lithium ion battery pack is in a charging state, and switch to supply power to the load by the lithium ion battery when the lithium ion battery pack finishes charging.

[0007] Further, the topology further comprises a fourth on-off component connected in parallel across the first diode, used to be closed to short circuit the first diode.

[0008] Further, the topology further comprises a fifth on-off component connected in parallel across the second diode, used to be closed to short circuit the second diode.

[0009] Further, the load comprises an AC load and a DC load, and the topology further comprises a DC / AC inverter arranged between the DC bus and the AC load, used to invert and filter the direct current output by the DC bus into alternating current.

[0010] Further, the topology further comprises a DC / DC converter arranged between the DC bus and the DC load, used to convert and filter the direct current output by the DC bus in voltage.

[0011] Further, the first, second, third, fourth and fifth on-off components are all contactors.

[0012] According to another aspect of the present application, an uninterrupted power supply method is provided, which adopts the uninterrupted power supply topology proposed in the foregoing of the present application, and the method comprises:

[0013] S1, when the lithium ion battery pack is in a power shortage state, connecting the power gun with an external DC source, and closing the first on-off component to make the power gun supply power to the load through the DC bus instead of the lithium ion battery pack;

[0014] S2, disconnecting the third on-off component and connecting the charging gun with the external DC source, and closing the second on-off component to charge the lithium ion battery pack through the charging gun;

[0015] S3, when charging to a preset time length, disconnecting the second on-off component and disconnecting the charging gun from the external DC source;

[0016] S4, closing the third on-off component;

[0017] S5, disconnecting the first on-off component and disconnecting the power gun from the external DC source to switch to supply power to the load by the lithium ion battery.

[0018] Further, the power supply gun in S1 replaces the lithium ion battery pack to supply power to the load through the DC bus line, comprising:

[0019] communicating with the power supply gun and the lithium ion battery pack to obtain the current voltage of the lithium ion battery pack;

[0020] gradually increasing the output voltage from 0V to a first preset voltage by the power supply gun, the first preset voltage being higher than the current voltage of the lithium ion battery pack.

[0021] Further, comprising between S3 and S4:

[0022] communicating with the power supply gun and the lithium ion battery pack to obtain the voltage when the lithium ion battery pack is charged for a preset time length;

[0023] gradually increasing the output voltage from the first preset voltage to a second preset voltage by the power supply gun, the second preset voltage being higher than the voltage when the lithium ion battery pack is charged for a preset time length.

[0024] Further, comprising between S4 and S5: gradually reducing the output voltage from the second preset voltage to 0V by the power supply gun.

[0025] The technical scheme of the application provides a DC source-based uninterrupted power supply topology and method, which connects the power supply gun and the lithium ion battery pack together through the DC bus line by setting the charging gun on the lithium ion battery pack, sets a diode between the lithium ion battery pack and the DC bus line, and sets on-off components between the power supply gun and the DC bus line, between the charging gun and the lithium ion battery pack, and between the lithium ion battery pack and the diode, thereby forming a topology structure containing two power sources of the lithium ion battery pack and the external DC source. Through the cooperation of the on-off components, the charging gun and the power supply gun, seamless switching can be realized between the lithium ion battery pack and the external CD source, uninterrupted power supply on the load side is realized, and the risk of thermal runaway is effectively reduced by the forward conduction characteristic of the diode. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings, which constitute a part of the specification, illustrate embodiments of the present application and serve to explain the principles of the present application. It is apparent that the accompanying drawings are only some embodiments of the present application and other drawings can be obtained by those skilled in the art without creative effort based on the accompanying drawings.

[0027] Figure 1 FIG. 1 shows a schematic diagram of a DC source-based uninterrupted power supply topology according to an embodiment of the present application. DETAILED DESCRIPTION

[0028] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other in the case of no conflict. The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The description of the at least one example embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0029] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of a feature, step, operation, device, component and / or combination thereof.

[0030] Unless specifically stated otherwise, the relative arrangements of the components and steps, numerical expressions, and numerical values set forth in the various examples herein are not limiting of the scope of the application. Also, it is to be understood that the various equivalents can be employed in accordance with common practice in the art, without departing from the scope of the application. In addition, any one of the features, steps or components can be employed in the practice of the application, in combination with other features, steps or components, without departing from the scope of the application. Any specific values should be interpreted as examples only, and not as limiting the scope of the inventive examples. Thus, other examples of the inventive examples can have different values. It is noted that like references herein to structures, materials or sections are meant to be references to like structures, materials, or sections throughout the disclosure, and thus, there is no need to discuss the same structures, materials or sections further in connection with other drawings.

[0031] According to an aspect of the present application, a DC source based uninterrupted power supply topology is provided, the topology comprising a power supply gun, a charging gun, a lithium ion battery pack, a first diode, a second diode, a DC bus, a load, a first switch, a second switch and a third switch, the charging gun and the power supply gun are connected with an external DC source, the DC bus is connected with the load, the power supply gun is connected with the DC bus, one end of the lithium ion battery pack is connected with the charging gun, the other end is connected with the anode of the first diode, the cathode of the first diode is connected with the DC bus, the anode of the second diode is connected with the third switch, and the cathode is connected with the DC bus.

[0032] The first on-off component is arranged between the power supply gun and the DC bus, is used for closing to supply power to the load through the power supply gun by the external DC source, and is used for opening to stop power supply; the second on-off component is arranged between the charging gun and the lithium ion battery pack, is used for closing to charge the lithium ion battery through the charging gun by the external DC source, and is used for opening to stop charging; and the third on-off component is arranged between the lithium ion battery pack and the diode, is used for closing to supply power to the load by the lithium ion battery pack, and is used for opening to stop power supply.

[0033] The charging gun is used for cooperating with the first on-off component, the second on-off component and the third on-off component to charge the lithium ion battery when the lithium ion battery pack is in a power shortage state; the power supply gun is used for cooperating with the first on-off component, the second on-off component and the third on-off component to supply power to the load by the lithium ion battery pack instead of the lithium ion battery pack when the lithium ion battery pack is in a charging state, and is switched to supply power to the load by the lithium ion battery when the lithium ion battery pack finishes charging.

[0034] The DC bus refers to a common bus of two DC power sources of the lithium ion battery pack and the ground charging pile, and the external DC source can be selected from a ground DC charging device.

[0035] By using the configuration mode, an uninterrupted power supply topology based on a DC source is provided. The topology connects the power supply gun and the lithium ion battery pack together by the DC bus through arranging the charging gun on the lithium ion battery pack, and sets a diode between the lithium ion battery pack and the DC bus, and sets on-off components between the power supply gun and the DC bus, between the charging gun and the lithium ion battery pack, and between the lithium ion battery pack and the diode, to form a topology structure containing two power sources of the lithium ion battery pack and the external DC source. The uninterrupted power supply topology can realize seamless switching between the lithium ion battery pack and the external CD source through the cooperation of the on-off components and the charging gun and the power supply gun, and realizes uninterrupted power supply on the load side. The forward conduction characteristic of the diode can avoid the lithium ion battery pack from discharging while charging, and effectively reduce the risk of thermal runaway. Compared with the prior art, the technical scheme of the present application can solve the technical problem that the lithium ion battery pack is prone to thermal runaway while discharging while charging in the uninterrupted power supply scenario.

[0036] Further, in order to prevent the diode from generating a large amount of heat for a long time, in the embodiment of the present application, the topology structure is further configured to include a fourth on-off component connected in parallel across the first diode, and is used for closing to short-circuit the first diode. By using this configuration mode, the fourth on-off component can be opened to utilize the forward conduction and reverse blocking characteristics of the first diode to complete seamless switching of the power source in a short time when it is necessary to switch the power source, and the fourth on-off component can be closed to short-circuit the first diode to avoid heating of the first diode when the power source is switched and the topology structure enters a long-time stable power supply state, thereby significantly improving the service life of the first diode.

[0037] In addition, in the embodiment of the present application, the topology further comprises a fifth on-off component connected in parallel across the second diode, for closing to short-circuit the second diode. Through such a configuration, the fifth on-off component can be opened to utilize the forward conduction and reverse blocking characteristics of the second diode to complete seamless switching of the power supply in a short time when switching of the power supply is required, and the fifth on-off component is closed to short-circuit the second diode to avoid heating thereof when entering a long-time stable power supply state after completion of the power supply switching, thereby significantly improving the service life of the second diode.

[0038] Further, the load comprises an AC load and a DC load, and the topology further comprises a DC / AC inverter arranged between the DC bus and the AC load, for inverting the DC power output by the DC bus into AC power and performing filtering processing. The AC load is also referred to as an alternating current load, and the DC load is also referred to as a direct current load. The DC / AC inverter has functions of inverting DC power into AC power and electromagnetic interference filtering, and through such a configuration, the DC power output by the DC bus can be used to supply power to the AC load, to ensure that the inverted voltage matches the rated operating voltage of the AC load to be powered and effectively reduces current ripple, thereby improving the applicability of the topology.

[0039] In the embodiment of the present application, the types of the first on-off component, the second on-off component, the third on-off component, the fourth on-off component, and the fifth on-off component are determined as required. As one specific embodiment of the present application, the first on-off component, the second on-off component, the third on-off component, the fourth on-off component, and the fifth on-off component are all contactors. The auxiliary contact of the contactor can be used to realize automatic triggering, thereby improving the automatic control level of the entire structure.

[0040] In addition, in the embodiment of the present application, the topology further comprises a DC / DC converter arranged between the DC bus and the DC load, for performing voltage conversion and filtering processing on the DC power output by the DC bus. The DC / DC converter has functions of step-up or step-down conversion of DC power and electromagnetic interference filtering, and through such a configuration, the voltage of the DC power output by the DC bus is ensured to match the rated operating voltage of the DC load to be powered and the current ripple is reduced, thereby improving the applicability of the topology and supplying power to various DC loads.

[0041] According to another aspect of the present application, an uninterrupted power supply method is provided, which adopts the uninterrupted power supply topology proposed in the foregoing embodiments of the present application, and the method comprises:

[0042] S1, when the lithium ion battery pack is depleted, connecting the power supply gun with an external DC source, and closing the first on-off component to make the power supply gun replace the lithium ion battery pack to supply power to the load through the DC bus;

[0043] S2, disconnecting the third switch component and connecting the charging gun with the external DC source, and closing the second switch component to charge the lithium ion battery pack through the charging gun;

[0044] S3, disconnecting the second switch component and disconnecting the charging gun from the external DC source when charging to a preset time length;

[0045] S4, closing the third switch component;

[0046] S5, disconnecting the first switch component and disconnecting the power gun from the external DC source to switch to power the load by the lithium ion battery.

[0047] In this way, an uninterrupted power supply method is provided, by which the lithium ion battery pack can normally power the load when it can supply power externally, and seamlessly switch to power the load by the external DC source when it needs to be charged, while charging the lithium ion battery pack by the external DC source, and can seamlessly switch from the external DC source to the lithium ion battery pack when the external DC source needs to be disconnected, so as to realize uninterrupted power supply on the load side, while avoiding the lithium ion battery pack discharging while charging, significantly reducing the risk of thermal runaway, and improving the safety and reliability of the lithium ion battery pack.

[0048] Further, in the embodiment of the present application, the power gun replaces the lithium ion battery pack to power the load through the DC bus in S1, comprising:

[0049] communicating with the lithium ion battery pack by the power gun to obtain the current voltage of the lithium ion battery pack;

[0050] gradually increasing the output voltage from 0V to a first preset voltage by the charging gun, the first preset voltage being higher than the current voltage of the lithium ion battery pack.

[0051] Wherein, the difference between the first preset voltage and the current voltage of the lithium ion battery pack is determined according to the need, which is usually slightly larger.

[0052] In addition, in the embodiment of the present application, between S3 and S4, comprising:

[0053] communicating with the lithium ion battery pack by the power gun to obtain the voltage of the lithium ion battery pack when charging to a preset time length;

[0054] gradually increasing the output voltage from the first preset voltage to a second preset voltage by the charging gun, the second preset voltage being higher than the voltage of the lithium ion battery pack when charging to a preset time length.

[0055] The difference between the second preset voltage and the voltage of the lithium ion battery pack when charged for a preset time period is determined according to requirements, and is usually slightly greater.

[0056] Further, the embodiment of the present application comprises gradually reducing the output voltage from the second preset voltage to 0V by using the power supply gun between S4 and S5. By this configuration, the smooth switching of the power supply can be realized, and the damage to the load can be avoided.

[0057] In order to better understand the power supply method provided by the present application, the following will be described in combination with Figure 1 The flow of the method is described by example, according to Figure 1 In the embodiment, S1 is the first on-off component, S3 is the second on-off component, S4 is the third on-off component, S5 is the fourth on-off component, S2 is the fifth on-off component, D1 is the first diode, and D2 is the second diode. In order to describe the cooperation relationship between each device or component in detail, it is assumed that the working voltage range of the lithium ion battery pack is 500V-720V, that is, the voltage of the lithium ion battery pack after being fully charged is 720V, and the voltage after being discharged is 500V. The working principle of uninterrupted power supply is that the lithium ion battery pack is used to supply power to the load under normal circumstances. When the lithium ion battery pack is charged, the ground equipment is used to supply power to the load in order to avoid the lithium ion battery pack being discharged while being charged, and the ground equipment and the lithium ion battery pack can realize seamless switching power supply. The specific process is as follows:

[0058] 1) Under normal circumstances, the rear-end load is supplied by the lithium ion battery pack. At this time, the states of the contactors are S1, S2 and S3 are opened, and S4 and S5 are closed. The DC power output by the lithium ion battery pack is converted by the DC / DC converter and the DC / AC inverter to supply power to the DC load and the AC load of different voltage levels.

[0059] 2) When the lithium ion battery pack is discharged and needs to be charged, the ground power supply gun is connected, the contactor S5 is disconnected and the contactor S1 is closed, the power supply gun communicates with the lithium ion battery pack. At this time, the voltage of the lithium ion battery pack is 500V, the output voltage of the power supply gun is slowly increased from 0V to 510V, at this time the load is supplied by the power supply gun. Similarly, the DC power output by the power supply gun is converted by the DC / DC converter and the DC / AC inverter to supply power to the DC load and the AC load of different voltage levels. Then, the contactor S4 is disconnected and the contactor S2 is closed, the ground charging gun is connected, the charging gun communicates with the lithium ion battery pack, the output voltage of the charging gun changes with the voltage of the battery pack and is slightly higher than the voltage of the battery pack, the contactor S3 is closed, and the charging gun charges the lithium ion battery pack.

[0060] 3) When the lithium ion battery pack is fully charged, the voltage returns to 720V, at this time, the contactor S3 is disconnected and the charging gun is pulled out, the output voltage of the power supply gun is set to slowly increase from 510V to 730V, the contactors S2 and S5 are disconnected and the contactor S4 is closed. Then, the output voltage of the power supply gun is set to slowly decrease from 730V to 0V, at this time, the load is powered by the lithium ion battery pack, the contactor S1 is disconnected and the power supply gun is pulled out, and the contactor S5 is closed.

[0061] Based on the above embodiment, a different power supply idea for different areas is provided, that is, the ground charging pile device in the base station is used to supply power to the load in the station, and the lithium battery pack is used to supply power to the load outside the base station, so that the lithium ion battery pack has sufficient power when working in the area outside the base station. In addition, the voltage range of the lithium ion battery pack can be adjusted according to different application scenarios, that is, the uninterrupted power supply topology and the corresponding power supply method can be applied to various scenarios.

[0062] In summary, the present application provides an uninterrupted power supply topology based on a DC source and an uninterrupted power supply method. The topology connects the power supply gun and the lithium ion battery pack together through the DC bus by setting the charging gun on the lithium ion battery pack, and sets a diode between the lithium ion battery pack and the DC bus. At the same time, the on-off components are set between the power supply gun and the DC bus, between the charging gun and the lithium ion battery pack, and between the lithium ion battery pack and the diode. The topology structure contains two power sources, lithium ion battery pack and external DC source. Through the cooperation of the on-off components and the charging gun and the power supply gun, seamless switching can be realized between the lithium ion battery pack and the external CD source, and uninterrupted power supply on the load side can be realized. At the same time, the forward conduction characteristic of the diode can avoid the lithium ion battery pack from charging and discharging at the same time, effectively reducing the risk of thermal runaway. Compared with the prior art, the technical scheme of the present application can solve the technical problem that the lithium ion battery pack is easy to have thermal runaway when charging and discharging at the same time in the uninterrupted power supply scene.

[0063] In the description of the present application, it should be understood that the orientation words such as "front, rear, upper, lower, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicate the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and in the absence of the opposite description, these orientation words do not indicate and imply that the indicated device or element must have a specific orientation or be constructed and operated in a specific orientation, therefore it cannot be understood as a limitation on the protection scope of the present application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0064] For purposes of the description hereinafter, spatial or directional terms, for example, "above", "below", "upper", "lower", and the like, can be used, and relate to the device as illustrated in the figures. However, it is to be understood that no absolute or relative orientation of the device is intended or implied, unless specifically described as such. Terms concerning attachments, coupling and the like, such as "connected" and "coupled" and the like, are to be construed in accordance with their normal meanings, that is, as referring to an indirect or direct connection or coupling. Any reference to "comprising" or "containing" is to be construed as meaning "comprising or containing, but not limited to". Any reference to "comprising" or "containing" is to be construed as meaning "comprising or containing, but not limited to".

[0065] In addition, it should be pointed out that the use of the terms "first", "second" and the like, to describe various elements in the claims, is merely intended to distinguish between two steps or entities of the application, and is not intended to limit the scope of the present application, unless specifically stated otherwise. Thus, the terms "first", "second", and the like, are not intended to limit the scope of the present application, unless specifically stated otherwise.

[0066] The preferred embodiments herein disclosed are not intended to limit the scope of the application, but rather the application is to cover all modifications and alternatives within the scope and spirit of the application. Therefore, the above description should not be construed as limiting, but merely as illustrative of the present application.

Claims

1. A DC-source-based uninterruptible power supply topology, characterized in that, The topology includes a power supply gun, a charging gun, a lithium-ion battery pack, a first diode, a second diode, a DC bus, a load, a first switching component, a second switching component, and a third switching component. The charging gun and the power supply gun are both connected to an external DC source. The DC bus is connected to the load. The power supply gun is connected to the DC bus. One end of the lithium-ion battery pack is connected to the charging gun, and the other end is connected to the anode of the first diode. The cathode of the first diode is connected to the DC bus. The anode of the second diode is connected to the third switching component, and the cathode is connected to the DC bus. The first switching component is disposed between the power supply gun and the DC bus, and is used to close to supply power to the load through the power supply gun using the external DC source and to disconnect to stop supplying power. The second switching component is disposed between the charging gun and the lithium-ion battery pack, and is used to close to charge the lithium-ion battery through the charging gun using the external DC source and to disconnect to stop charging. The third switching component is disposed between the lithium-ion battery pack and the diode, and is used to close to supply power to the load through the lithium-ion battery pack and to disconnect to stop supplying power. The charging gun is used in conjunction with the first switching component, the second switching component, and the third switching component to charge the lithium-ion battery when the lithium-ion battery pack is depleted. The power supply gun is used in conjunction with the first switching component, the second switching component, and the third switching component to replace the lithium-ion battery pack in supplying power to the load when the lithium-ion battery pack is charging, and to switch to supplying power to the load by the lithium-ion battery when the lithium-ion battery pack finishes charging. The method for uninterrupted power supply using the aforementioned topology includes: S1, when the lithium-ion battery pack is depleted, connecting the power supply gun to an external DC source and closing the first switching component to allow the power supply gun to supply power to the load through the DC bus instead of the lithium-ion battery pack; S2, disconnecting the third switching component and connecting the charging gun to the external DC source, and closing the second switching component to charge the lithium-ion battery pack through the charging gun; S3, when charging reaches a preset duration, disconnecting the second switching component and disconnecting the charging gun from the external DC source; S4, closing the third switching component; S5, disconnecting the first switching component and disconnecting the power supply gun from the external DC source to switch the load to be powered by the lithium-ion battery. The power supply gun in S1, which replaces the lithium-ion battery pack to supply power to the load through the DC bus, includes: using the power supply gun to communicate with the lithium-ion battery pack to obtain the current voltage of the lithium-ion battery pack; and using the charging gun to gradually increase the output voltage from 0V to a first preset voltage, wherein the first preset voltage is higher than the current voltage of the lithium-ion battery pack. Between S3 and S4, the process includes: using the power supply gun to communicate with the lithium-ion battery pack to obtain the voltage of the lithium-ion battery pack when it is charged to a preset duration; using the power supply gun to gradually increase the output voltage from the first preset voltage to a second preset voltage, wherein the second preset voltage is higher than the voltage of the lithium-ion battery pack when it is charged to a preset duration.

2. The topology according to claim 1, characterized in that, The topology also includes a fourth switching component, which is connected in parallel across the first diode and is used to close the circuit to short-circuit the first diode.

3. The topology according to claim 2, characterized in that, The topology also includes a fifth switching component, which is connected in parallel across the two ends of the second diode and is used to close the circuit to short-circuit the second diode.

4. The topology according to claim 3, characterized in that, The load includes AC load and DC load. The topology also includes a DC / AC inverter, which is located between the DC bus and the AC load and is used to invert the DC power output from the DC bus into AC power and perform filtering.

5. The topology according to claim 4, characterized in that, The topology also includes a DC / DC converter, which is disposed between the DC bus and the DC load and is used to perform voltage transformation and filtering on the DC power output from the DC bus.

6. The topology according to any one of claims 1 to 5, characterized in that, The first switching component, the second switching component, the third switching component, the fourth switching component, and the fifth switching component are all contactors.

7. The topology according to claim 6, characterized in that, Between S4 and S5, the output voltage is gradually reduced from the second preset voltage to 0V using the power supply gun.

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