An energy storage charging and swapping system

Abstract

The present application discloses an energy storage charging and swapping system, a first switching unit connected to the power grid, a voltage conversion unit connected to the first switching unit, a second switching unit connected to the voltage conversion unit, an energy storage battery and a power battery respectively connected to the second switching unit, and a control unit respectively connected to the first switching unit and the second switching unit. Since the energy storage battery and the power battery are connected through the voltage conversion unit, during the process of the energy storage battery charging the power battery, the voltage conversion unit can achieve the energy conversion between the energy storage battery and the power battery through one energy conversion, improving the charging efficiency of the energy storage charging and swapping system, reducing the usage cost and usage space of the energy storage charging and swapping system.

Description

Technical Field

[0001] The present application relates to the technical field of power electronics, and particularly to an energy storage charging and swapping system. Background Art

[0002] With the development of technology, new energy electric vehicles, as a model of clean energy utilization, have gradually become the focus of the automotive industry and energy development, and have also gradually become an important part of human daily life.

[0003] In the current energy storage charging and swapping system, both the energy storage battery and the power battery are connected to the DC bus. In order to ensure the stability of the DC bus voltage, the voltage of the DC bus is constant. During the charging process of the energy storage battery to the power battery, it is necessary to pass through multiple DC / DC conversion units (for example: after the energy storage battery is connected to the bidirectional DC / DC conversion unit, the bidirectional DC / DC conversion unit is connected to the DC bus, after the DC bus is connected to the DC / DC conversion unit, the DC / DC conversion unit is then connected to the power battery) to meet the requirement of matching the output voltage of the energy storage battery with the charging demand of the power battery. Since the energy storage battery and the power battery need to be connected through the DC bus, when the energy storage battery charges multiple power batteries, multiple energy conversions are required, which reduces the charging efficiency of the energy storage charging and swapping system, increases the usage cost and usage space. In addition, since the charging and swapping system cannot supply power to new energy electric vehicles according to the peak-valley electricity rule, it often supplies power to the power battery during the peak electricity period, resulting in a higher electricity cost problem.

[0004] Therefore, it can be seen that how to improve the charging efficiency of the energy storage charging and swapping system, reduce the usage cost and usage space of the energy storage charging and swapping system is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of the present application is to provide an energy storage charging and swapping system to improve the charging efficiency of the energy storage charging and swapping system, reduce the usage cost and usage space of the energy storage charging and swapping system.

[0006] To solve the above technical problems, the present application provides an energy storage charging and swapping system, including: a first switch unit connected to the power grid, a voltage conversion unit connected to the first switch unit, a second switch unit connected to the voltage conversion unit, an energy storage battery and a power battery respectively connected to the second switch unit, and a control unit respectively connected to the first switch unit and the second switch unit;

[0007] The control unit is configured to control the first switch unit and the second switch unit to charge the energy storage battery through the voltage conversion unit from the power grid during a first preset time period, and control the first switch unit and the second switch unit to charge the power battery through the voltage conversion unit from the energy storage battery during a second preset time period; the control unit is further configured to realize the series connection and parallel connection between the energy storage battery packs in the energy storage battery through the second switch unit.

[0008] The voltage conversion unit is configured to output direct current that can meet the charging requirements of the energy storage battery when the power grid charges the energy storage battery, and convert the output of the energy storage battery into direct current that can meet the charging requirements of the power battery when the energy storage battery charges the power battery.

[0009] Preferably, the control unit is further configured to control the first switch unit and the second switch unit to charge the power battery through the voltage conversion unit from the power grid when the energy storage battery does not meet the preset conditions.

[0010] Wherein, the preset conditions are specifically that the energy storage battery works normally or the power of the energy storage battery meets the required power of the power battery.

[0011] Preferably, the second switch unit includes: a power battery switch group connected to the power battery and the voltage conversion unit, and a controllable switch array connected to the energy storage battery and the voltage conversion unit.

[0012] The control unit is configured to control the first switch unit to close, the power battery switch group to open, and the controllable switch array to make the energy storage battery packs in the energy storage battery in parallel or series connection during the first preset time period, and control the first switch unit to open, the power battery switch group to close, and the controllable switch array to make the energy storage battery packs in parallel or series connection during the second preset time period.

[0013] Preferably, the controllable switch array includes: a first switch group, a second switch group, a third switch group, a fourth switch group, and a fifth switch group. The first ends of the switches in the first switch group are connected to each other and then connected to the output end of the voltage conversion unit. The second ends of the switches in the first switch group are respectively connected to the energy storage battery packs one by one. The first ends of the switches in the second switch group are respectively connected to the energy storage battery packs one by one. The second ends of the switches in the second switch group are connected to each other and then connected to the output end of the voltage conversion unit. The first ends of the switches in the third switch group and the fourth switch group are respectively connected to the energy storage battery packs one by one. The second ends of the switches in the third switch group and the fourth switch group are connected to each other and then connected to the input end of the voltage conversion unit. The first ends of the switches in the fifth switch group are correspondingly connected to the first ends of the switches in the third switch group. The second ends of the switches in the fifth switch group are respectively connected to the energy storage battery packs and the first ends of the switches in the fourth switch group one by one.

[0014] Preferably, when the power grid charges the energy storage batteries, the energy storage battery packs are connected in parallel or in series with each other. When the energy storage batteries charge the power batteries, the energy storage battery packs are connected in parallel or in series with each other.

[0015] Preferably, the voltage conversion unit is a two-stage circuit, with the front stage being an AC / DC conversion circuit and the rear stage being a DC / DC conversion circuit.

[0016] Preferably, the AC / DC conversion circuit is a VIENNA circuit.

[0017] Preferably, the AC / DC conversion circuit is a rectifier bridge and a Boost circuit connected after the rectifier bridge.

[0018] Preferably, the DC / DC conversion circuit is an isolated DC / DC circuit or a non-isolated DC / DC circuit.

[0019] Preferably, the first preset time period is a valley electricity time period, and the second preset time period is a non-valley electricity time period.

[0020] The energy storage charging and swapping system provided by this application includes a first switch unit connected to the power grid, a voltage conversion unit connected to the first switch unit, a second switch unit connected to the voltage conversion unit, an energy storage battery and a power battery respectively connected to the second switch unit, and a control unit respectively connected to the first switch unit and the second switch unit. The control unit is used to charge the energy storage battery from the power grid through the voltage conversion unit in a first preset time period, and to charge the power battery from the energy storage battery through the voltage conversion unit in a second preset time period. Since the energy storage battery and the power battery are connected through the voltage conversion unit, during the process of the energy storage battery charging the power battery, the voltage conversion unit can achieve the energy conversion between the energy storage battery and the power battery through one energy conversion, without multiple DC / DC conversion units performing multiple energy conversions, improving the charging efficiency of the energy storage charging and swapping system, reducing the usage cost and usage space of the energy storage charging and swapping system. In addition, since the control unit can control the energy storage battery to be charged in the first preset time period and supply power to the power battery through the energy storage battery in the second preset time period, the charging and swapping system can choose to store the voltage of the power grid in the energy storage battery in the first preset time period and be powered by the energy storage battery in the second preset time period, thereby reducing the electricity cost of the charging and swapping system.

[0021] At the same time, the voltage conversion unit in this application integrates an AC / DC conversion circuit and a DC / DC conversion circuit. The energy of the power grid can be converted by the voltage conversion unit to charge the energy storage battery and the power battery, and at the same time, the energy storage battery can also charge the power battery of the electric vehicle through this voltage conversion unit. This design helps to improve the system efficiency. Compared with the prior art, two sets of DC / DC circuits can be saved for each charging battery unit, and the cost is lower. Brief Description of the Drawings

[0022] In order to more clearly illustrate the embodiments of this application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 It is a circuit diagram of an energy storage charging and swapping system provided by an embodiment of this application;

[0024] Figure 2 It is a circuit diagram of a voltage conversion unit provided by an embodiment of this application;

[0025] Figure 3 It is a circuit diagram of another voltage conversion unit provided by an embodiment of this application. Detailed Embodiments

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in 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. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present application.

[0027] The core of the present application is to provide an energy storage charging and swapping system to improve the charging efficiency of the energy storage charging and swapping system, reduce the usage cost and usage space of the energy storage charging and swapping system.

[0028] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the present application will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present application.

[0029] Figure 1 This is a circuit diagram of an energy storage charging and swapping system provided for an embodiment of the present application. As Figure 1 shown, the energy storage charging and swapping system includes: a first switch unit 10 connected to the power grid, a voltage conversion unit 11 connected to the first switch unit 10, a second switch unit 12 connected to the voltage conversion unit 11, an energy storage battery 13 and a power battery 15 respectively connected to the second switch unit 12, and a control unit 14 respectively connected to the first switch unit 10 and the second switch unit 12.

[0030] The control unit 14 is used to control the first switch unit 10 and the second switch unit 12 to charge the energy storage battery 13 through the voltage conversion unit 11 from the power grid during a first preset time period, and control the first switch unit 10 and the second switch unit 12 to charge the power battery 15 through the voltage conversion unit 11 from the energy storage battery 13 during a second preset time period; the control unit 14 is further used to realize the series connection and parallel connection of the energy storage battery compartments in the energy storage battery 13 through the second switch unit 12.

[0031] The voltage conversion unit 11 is used to output direct current that can meet the charging requirements of the energy storage battery 13 when the power grid charges the energy storage battery 13, and convert the output of the energy storage battery 13 into direct current that can meet the charging requirements of the power battery 15 when the energy storage battery 13 charges the power battery 15.

[0032] It should be noted that in a battery swapping station, the power battery 15 refers to the battery for rapid battery swapping of an electric vehicle; in a charging station, the power battery 15 refers to the battery in the electric vehicle. In addition, the energy storage battery 13 can be a brand-new battery purchased separately or a power battery 15 retired from an electric vehicle.

[0033] In a specific implementation, the voltage conversion unit 11 converts the input signal of the power grid into the input signal of the energy storage battery 13 and / or the power battery 15 according to a charging curve with time as a variable.

[0034] In a specific implementation, the voltage conversion unit 11 converts the input signal of the power grid into the input signal of the energy storage battery 13 and / or the power battery 15 that meets the requirements of the Battery Management System (BMS). The voltage conversion unit 11 is circuit-coupled, with an AC / DC conversion circuit at the front stage and a DC / DC conversion circuit at the rear stage.

[0035] Among them, the DC / DC conversion circuit can be an isolated DC / DC circuit or a non-isolated DC / DC circuit; the AC / DC conversion circuit can be a three-phase three-level (VIENNA) circuit, or a connection circuit of a rectifier bridge and a boost (Boost) circuit or other AC / DC conversion circuits. The first preset time period is specifically the valley electricity time period, and the second preset time period is specifically the non-valley electricity time period, that is, the valley electricity time period and the non-valley electricity time period stipulated by the municipality. It can be imagined that when the municipal regulations change, the valley electricity time period and the non-valley electricity time period will change accordingly.

[0036] Figure 2 This is a circuit diagram of a voltage conversion unit provided by an embodiment of the present application. As Figure 2 shown, the voltage conversion unit 11 includes a Boost circuit 30 and an isolated DC / DC circuit 31. The input end of the Boost circuit 30 is respectively connected to the three-phase circuit of the power grid, and the output end of the Boost circuit 30 is respectively connected to the input end of the isolated DC / DC circuit 31. Among them, the Boost circuit 30 is composed of a diode group, an inductor, a capacitor, and a controllable switch.

[0037] Figure 3 This is another circuit diagram of a voltage conversion unit provided by an embodiment of the present application. As Figure 3 shown, the voltage conversion unit 11 includes a VIENNA circuit 32 and a non-isolated DC / DC circuit 33. The input end of the VIENNA circuit 32 is respectively connected to the three-phase circuit of the power grid, and the output end of the VIENNA circuit 32 is respectively connected to the input end of the non-isolated DC / DC circuit 33. Among them, the VIENNA circuit 32 is composed of an inductor, a diode group, a switch tube group, and a capacitor.

[0038] The energy storage charging and swapping system provided by the embodiment of the present application includes a first switch unit connected to the power grid, a voltage conversion unit connected to the first switch unit, a second switch unit connected to the voltage conversion unit, an energy storage battery and a power battery respectively connected to the second switch unit, and a control unit respectively connected to the first switch unit and the second switch unit. The control unit is configured to charge the energy storage battery through the voltage conversion unit from the power grid during a first preset time period, and charge the power battery through the voltage conversion unit from the energy storage battery during a second preset time period. Since the energy storage battery and the power battery are connected through the voltage conversion unit, during the process of the energy storage battery charging the power battery, the voltage conversion unit can achieve the energy conversion between the energy storage battery and the power battery through one energy conversion, without the need for multiple DC / DC conversion units to perform multiple energy conversions, improving the charging efficiency of the energy storage charging and swapping system, reducing the usage cost and usage space of the energy storage charging and swapping system. In addition, since the control unit can control the energy storage battery to charge during the first preset time period and supply power to the power battery through the energy storage battery during the second preset time period, the charging and swapping system can choose to store the voltage of the power grid in the energy storage battery during the first preset time period and be powered by the energy storage battery during the second preset time period, thereby reducing the power consumption cost of the charging and swapping system.

[0039] At the same time, the voltage conversion unit in the present application integrates an AC / DC conversion circuit and a DC / DC conversion circuit. The energy of the power grid can be converted by the voltage conversion unit to charge the energy storage battery and the power battery, and at the same time, the energy storage battery can also charge the power battery of the electric vehicle through the voltage conversion unit. This design helps to improve the system efficiency. Compared with the prior art, two sets of DC / DC circuits can be saved for each charging battery unit, and the cost is lower.

[0040] On the basis of the above embodiment, the control unit 14 is further configured to control the power grid to charge the power battery 15 through the first switch unit 10 and the second switch unit 12 when the energy storage battery 13 does not meet the preset conditions.

[0041] Wherein, the preset condition is that the energy storage battery 13 works normally or the power of the energy storage battery 13 meets the required power of the power battery 15.

[0042] It can be understood that when the power of the energy storage battery 13 cannot meet the demand for charging the power battery 15, or the energy storage battery 13 works abnormally, the control unit 14 can also control the first switch unit 10 and the second switch unit 12 to enable the power grid to charge the power battery 15 through the voltage conversion unit 11, so as to ensure that the power battery 15 can be charged normally, thereby ensuring the user experience.

[0043] Such as Figure 1As shown, based on the above embodiments, the second switch unit 12 includes: a power battery switch group 20 connected to the power battery 15 and the voltage conversion unit 11, and a controllable switch array connected to the energy storage battery 13 and the voltage conversion unit 11.

[0044] The control unit 14 is configured to control the first switch unit 10 to be closed, the power battery switch group 20 to be opened, and the controllable switch array to connect the energy storage battery packs in the energy storage battery 13 in parallel or in series during a first preset time period, and to control the first switch unit 10 to be opened, the power battery switch group 20 to be closed, and the controllable switch array to connect the energy storage battery packs in parallel or in series during a second preset time period.

[0045] As a preferred embodiment, in a specific implementation, when the power grid charges the energy storage battery 13, the energy storage battery packs are connected in parallel or in series, and when the energy storage battery 13 charges the power battery 15, the energy storage battery packs are connected in parallel or in series. Since the connection relationship between the energy storage battery packs is not limited when the power grid charges the energy storage battery 13 or the energy storage battery 13 charges the power battery 15, the flexibility of the energy storage charging and swapping system is improved.

[0046] To improve the working efficiency of the energy storage charging and swapping system, as a preferred embodiment, the control unit 14 is further configured to, when the energy storage battery 13 charges the power battery 15, select a target energy storage battery pack that is most matched to the power battery 15 according to preset parameters, and control the target energy storage battery pack to charge the power battery 15 through the switch corresponding to the target energy storage battery pack in the controllable switch array.

[0047] It should be noted that the preset parameters are one or more of the voltage of the energy storage battery 13, the voltage of the power battery 15, the discharge current of the energy storage battery 13, and the battery capacity of the energy storage battery 13.

[0048] In addition, to further improve the working efficiency of the energy storage charging and swapping system, during the process of the energy storage battery 13 charging the power battery 15, the control unit 14 is further configured to re-select a target energy storage battery pack that is most matched to the power battery 15 according to preset parameters when the target energy storage battery 13 does not meet the preset requirements.

[0049] As Figure 1 shown, as a preferred embodiment, the controllable switch array includes: a first switch group 21, a second switch group 22, a third switch group 23, a fourth switch group 24, and a fifth switch group 25.

[0050] The first ends of the switches in the first switch group 21 are connected to each other and then connected to the output end of the voltage conversion unit 11. The second ends of the switches in the first switch group 21 are respectively connected to the energy storage battery packs one by one. The first ends of the switches in the second switch group 22 are respectively connected to the energy storage battery packs one by one. The second ends of the switches in the second switch group 22 are connected to each other and then connected to the output end of the voltage conversion unit 11. The first ends of the switches in the third switch group 23 and the fourth switch group 24 are respectively connected to the energy storage battery packs one by one. The second ends of the switches in the third switch group 23 and the fourth switch group 24 are connected to each other and then connected to the input end of the voltage conversion unit 11. The first ends of the switches in the fifth switch group 25 are correspondingly connected to the first ends of the switches in the third switch group 23. The second ends of the switches in the fifth switch group 25 are respectively and correspondingly connected to the energy storage battery packs and the first ends of the switches in the fourth switch group 24.

[0051] Then, the control unit 14 controls the controllable switch array to make the energy storage battery packs in the energy storage battery 13 be connected in parallel or in series specifically as follows:

[0052] Control the first switch group 21, the second switch group 22, the third switch group 23, and the fourth switch group 24 to be closed, and the fifth switch group 25 to be open, or control the first switch group 21 and the second switch group 22 to be closed, and the third switch group 23, the fourth switch group 24, and the fifth switch group 25 to be open, so that the energy storage battery packs are connected in parallel. Control the switches in the first switch group 21 and the second switch group 22 to be open, the third switch group 23 and the fourth switch group 24 to be open, and the fifth switch group 25 to be closed, so that the energy storage battery packs are connected in series. For example, the energy storage battery includes four energy storage battery packs. The first switch group 21 includes four switches. The second switch group 22 includes four switches. The switches in the first switch group 21 are denoted as the first switch, the second switch, the third switch, and the fourth switch from left to right. The switches in the second switch group 22 are denoted as the first switch, the second switch, the third switch, and the fourth switch from left to right. The switches in the third switch group 23 are denoted as the first switch, the second switch, the third switch, and the fourth switch from top to bottom. The switches in the fourth switch group 24 are denoted as the first switch, the second switch, the third switch, and the fourth switch from top to bottom.

[0053] Then, when the power grid charges the energy storage battery through the voltage conversion unit:

[0054] 1. The first switch unit 10 is closed, the switches in the first switch group 21 and the second switch group 22 are closed, the rest of the switches in the second switch unit 12 are open, and the rest of the switches realize parallel charging of the energy storage battery packs.

[0055] 2. The first switch unit 10 is closed, the first switch in the first switch group 21 is closed, the fourth switch in the second switch group 22 is closed, all the switches in the fifth switch group 25 are closed, and the rest of the switches in the second switch unit 12 are open, then series charging of the energy storage battery packs is realized.

[0056] When the energy storage battery discharges for the power battery:

[0057] 1. The first switch unit 10 is disconnected, the power battery switch group 20 is closed, the third switch group 23 and the fourth switch group 24 are closed, and the remaining switches in the second switch unit 12 are disconnected, then the parallel discharge of the energy storage battery pack is realized.

[0058] 2. The first switch unit 10 is disconnected, the power battery switch group 20 is closed, the first switch in the third switch group 23 is closed, the fourth switch in the fourth switch group 24 is closed, and the fifth switch group 25 is closed, then the series discharge of the energy storage battery pack is realized.

[0059] It should be noted that the specific structure of the above controllable switch array is a form of manifestation, which does not mean that there is only one form of manifestation.

[0060] The energy storage charging and swapping system provided by the embodiments of the present application can make the energy storage battery be connected in series or in parallel according to the user's needs during the charging or discharging process through the controllable switch array, improving the flexibility of the energy storage charging and swapping system.

[0061] On the basis of the above embodiments, the number of power batteries 15 is n (where n is a positive integer). Among them, the number of voltage conversion units 11 can be matched with the number of power batteries 15. When the number of voltage conversion units 11 is matched with the number of power batteries 15, the number of power battery switch groups 20 is matched with the number of power batteries 15 and is correspondingly connected to each power battery 15.

[0062] The above has introduced in detail an energy storage charging and swapping system provided by the present application. The embodiments in the specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same and similar parts among the embodiments can be referred to each other. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

[0063] It should also be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element.

Claims

1. A energy storage charging and swapping system, characterized in that, Comprising: A first switch unit connected to the power grid, a voltage conversion unit connected to the first switch unit, a second switch unit connected to the voltage conversion unit, a storage battery and a power battery respectively connected to the second switch unit, and a control unit respectively connected to the first switch unit and the second switch unit; The control unit is configured to control the first switch unit and the second switch unit in a first preset time period to charge the storage battery from the power grid through the voltage conversion unit, and control the first switch unit and the second switch unit in a second preset time period to charge the power battery from the storage battery through the voltage conversion unit; the control unit is further configured to realize the series connection and parallel connection between the storage battery packs in the storage battery through the second switch unit; The voltage conversion unit is configured to output direct current that can meet the charging requirements of the storage battery when the power grid charges the storage battery, and convert the output of the storage battery into direct current that can meet the charging requirements of the power battery when the storage battery charges the power battery; The control unit is further configured to control the first switch unit and the second switch unit to charge the power battery from the power grid through the voltage conversion unit when the storage battery does not meet the preset conditions; Wherein, the preset conditions are specifically that the storage battery works normally or the power of the storage battery meets the required power of the power battery; The second switch unit includes: a power battery switch group connected to the power battery and the voltage conversion unit, and a controllable switch array connected to the storage battery and the voltage conversion unit; The control unit is configured to control the first switch unit to close, the power battery switch group to open, and the controllable switch array to make the storage battery packs in the storage battery connected in parallel or in series in the first preset time period, and control the first switch unit to open, the power battery switch group to close, and the controllable switch array to make the storage battery packs connected in parallel or in series in the second preset time period; The controllable switch array includes: a first switch group, a second switch group, a third switch group, a fourth switch group, and a fifth switch group. The first ends of the switches in the first switch group are connected to each other and then connected to the output end of the voltage conversion unit. The second ends of the switches in the first switch group are respectively connected to the energy storage battery packs one by one. The first ends of the switches in the second switch group are respectively connected to the energy storage battery packs one by one. The second ends of the switches in the second switch group are connected to each other and then connected to the output end of the voltage conversion unit. The first ends of the switches in the third switch group and the fourth switch group are respectively connected to the energy storage battery packs one by one. The second ends of the switches in the third switch group and the fourth switch group are connected to each other and then connected to the input end of the voltage conversion unit. The first ends of the switches in the fifth switch group are correspondingly connected to the first ends of the switches in the third switch group. The second ends of the switches in the fifth switch group are respectively and correspondingly connected to the energy storage battery packs and the first ends of the switches in the fourth switch group one by one; The voltage conversion unit is a two-stage circuit. The front stage is an AC / DC conversion circuit, and the rear stage is a DC / DC conversion circuit.

2. The energy storage charging and swapping system according to claim 1, characterized in that, When the power grid charges the energy storage battery, the energy storage battery packs are connected in parallel or in series with each other. When the energy storage battery charges the power battery, the energy storage battery packs are connected in parallel or in series with each other.

3. The energy storage charging and swapping system according to claim 1, characterized in that, The AC / DC conversion circuit is a VIENNA circuit.

4. The energy storage charging and swapping system according to claim 1, characterized in that, The AC / DC conversion circuit is a rectifier bridge and a Boost circuit connected after the rectifier bridge.

5. The energy storage charging and swapping system according to claim 1, characterized in that, The DC / DC conversion circuit is an isolated DC / DC circuit or a non-isolated DC / DC circuit.

6. The energy storage charging and swapping system according to claim 1, characterized in that, The first preset time period is the valley electricity time period, and the second preset time period is the non-valley electricity time period.

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