Direct current interconnection battery charging and replacing system

Abstract

The invention relates to the technical field of charging and battery swapping, particularly provides a direct current interconnection charging and battery swapping system, and aims to solve the problems that the cost of an energy storage system and a photovoltaic power generation system configured in an existing charging and battery swapping field station is relatively high, and the capacity help is limited during peak hours. In order to achieve the purpose, the direct-current interconnection battery charging and swapping system comprises at least two direct-current partitions, each direct-current partition comprises a direct-current bus, an AC / DC converter, a DC / DC converter and battery charging and swapping equipment, the direct-current buses are connected with an alternating-current power grid through the AC / DC converters, and the battery charging and swapping equipment is connected with the direct-current buses through the DC / DC converters; the direct current bus of each direct current subarea is connected with the direct current bus of at least another direct current subarea through the subarea connecting device, and the subarea connecting device at least can control connection and disconnection between the two direct current buses which are connected with each other. According to the invention, the space-time complementation characteristic of the load of each station can be fully utilized, the load fluctuation is stabilized, the capacity ataxia is realized, and the investment for equipping an energy storage device is reduced.

Description

Technical Field

[0001] This invention relates to the field of charging and swapping technology, and specifically provides a DC interconnected charging and swapping system. Background Technology

[0002] Currently, my country's power system is in a transitional period from traditional energy (thermal power, hydropower, etc.) power generation as the main source to new energy (wind power, solar power, etc.) power generation as the main source. The new energy power system has two distinct characteristics: First, from the power supply side, new energy power generation exhibits a significant imbalance in both time and spatial scales compared to traditional energy power generation. Second, from the electricity consumption side, due to the rapid growth in the number of new energy vehicles, especially electric vehicles, in recent years, the impact of charging load on the distribution network has begun to emerge in cities with high electric vehicle penetration rates, and the existing distribution network planning is no longer sufficient to cope with the increasing charging demand.

[0003] One important approach to solving these problems is to configure energy storage and photovoltaic (PV) power generation systems at charging stations to reduce reliance on distribution capacity and lower electricity costs. However, such systems typically use AC power, resulting in multiple energy conversion stages and generally high losses. To improve system efficiency, a new type of charging and battery swapping station with a common DC bus is gaining attention. This involves a single-stage rectifier system to obtain a low-voltage DC bus, such as 800V, and then connecting multiple DC / DC converters to this bus, which in turn connect to different charging terminals, energy storage devices, and PV modules. When the system's AC capacity is limited, or when a large amount of electricity comes from DC (energy storage or PV), the reduced number of conversion stages and AC transformers significantly improves system efficiency, making it well-suited for the energy demands of large or ultra-large charging centers with high electric vehicle penetration. While the common DC bus approach can address the low system efficiency to some extent, the high cost of configuring energy storage and PV systems can lead to redundant investment, hindering cost control during station deployment. Furthermore, the capacity provided by energy storage and PV systems is limited during peak charging periods.

[0004] Accordingly, a new technical solution is needed in this field to solve the above problems. Summary of the Invention

[0005] This application aims to solve at least one of the above-mentioned technical problems, namely, to address the issues that existing charging and swapping stations have high costs for configuring energy storage systems and photovoltaic power generation systems, and limited capacity assistance during peak periods.

[0006] In a first aspect, this application provides a DC interconnected charging and swapping system, comprising: at least two DC zones, each DC zone including a DC bus, an AC / DC converter, a DC / DC converter, and charging / swapping equipment, wherein the DC bus is connected to an AC power grid via the AC / DC converter, and the charging / swapping equipment is connected to the DC bus via the DC / DC converter; and a zone connection device, wherein the DC bus of each DC zone is connected to the DC bus of at least another DC zone via the zone connection device, and the zone connection device is capable of controlling the on / off state between at least two interconnected DC buses.

[0007] By adopting the above technical solution, this application can fully utilize the spatiotemporal complementarity of the loads at various charging stations, smooth load fluctuations, achieve capacity sharing, and significantly reduce investment in power distribution capacity expansion or energy storage devices. Specifically, due to differences in scenarios and user habits, electric vehicle charging facilities such as battery swapping stations, public charging piles, and home charging piles naturally exhibit spatiotemporal differences. For example, home charging piles typically concentrate on charging during off-peak hours at night, public charging piles usually have two distinct peak periods: midday and early morning. Battery swapping stations, due to different peak-shaving strategies and user types, exhibit different types of load characteristics. Overall, battery swapping stations, public charging piles, and home charging piles have complementary spatiotemporal characteristics. Compared to traditional charging and swapping equipment being connected to the grid separately, this application effectively utilizes this complementary characteristic by connecting DC buses under different DC zones through zoned connections. This enables capacity scheduling among multiple DC buses, improves the carrying capacity and service capacity of electric vehicles, reduces the number of energy storage devices and photovoltaic power generation devices, and avoids redundant investment in energy storage.

[0008] In the preferred technical solution of the above-mentioned DC interconnected charging and swapping system, the partition connection device includes a DC switch and an inrush current suppression circuit.

[0009] Setting up an inrush current suppression circuit can limit the huge inrush current generated at the moment of DC bus connection, thereby protecting the DC bus and ensuring the reliability of the system.

[0010] In the preferred embodiment of the DC interconnected charging and swapping system described above, the inrush current suppression circuit includes a current-limiting resistor and a bypass switch connected in parallel with each other.

[0011] In the preferred embodiment of the above-mentioned DC interconnected charging and swapping system, the partition connection device further includes a DC / DC converter, which is disposed between two interconnected DC buses.

[0012] By setting up a DC / DC converter, two DC zones with different voltages can be connected, improving the system's applicability.

[0013] In the preferred embodiment of the DC interconnected charging and swapping system described above, at least one of the DC zones is further provided with an energy storage device and / or a photovoltaic power generation device, and the energy storage device and / or the photovoltaic power generation device are connected to the DC bus via a DC / DC converter.

[0014] By setting up energy storage devices and / or photovoltaic power generation devices in DC partitions, the energy conversion stages are fewer compared to traditional AC coupling methods, and the system has higher efficiency and response speed in scenarios with limited AC penetration.

[0015] In the preferred embodiment of the above-mentioned DC interconnected charging and swapping system, the DC / DC converter is a converter with bidirectional short-circuit current interruption capability, and a first fuse is provided between the DC / DC converter and the DC bus, the fusing time of the first fuse being not less than 10ms; or the DC / DC converter is a converter with unidirectional short-circuit current interruption capability, and a second fuse is provided between the DC / DC converter and the DC bus on the side without current interruption capability, the fusing time of the second fuse being not greater than 5ms.

[0016] By using a DC / DC converter with bidirectional short-circuit current interruption capability, which can quickly shut off in the event of a short circuit, only a first fuse with a fusing time of not less than 10ms is required. However, for DC / DC converters with only unidirectional short-circuit current interruption capability, unlike traditional AC systems where short-circuit current can be protected by conventional AC circuit breakers and fuses with mature protection parameter setting methods, DC interconnected systems lack inductive reactance. When a short-circuit fault occurs, the system's short-circuit impedance is low, the steady-state short-circuit current is very high and rises rapidly, and the fault range is much larger than in AC interconnected systems, easily causing fault propagation and system shutdown. In particular, the short-circuit current in DC systems is direct current and has no zero-crossing point, making traditional DC circuit breakers ineffective at interrupting DC arcs. Using new power electronics-based DC circuit breakers results in high system costs, and traditional fuses have slow response times (fusing time exceeding tens of milliseconds), failing to meet the requirements for fast system protection. Therefore, a millisecond-level (no more than 5ms) ultra-fast fuse must be equipped on the side that cannot interrupt the current to ensure that the faulty partition can be isolated at the millisecond level, so that the fault will not spread and will not affect the normal operation of other partitions of the system.

[0017] In the preferred technical solution of the above-mentioned DC interconnected charging and swapping system, a dynamic braking circuit is also provided on the DC bus, and the dynamic braking circuit is configured to stabilize the voltage of the DC bus.

[0018] By setting up a dynamic braking circuit, it is possible to effectively respond to frequent fault modes (sudden stop during charging) when electric vehicles are recharged, so that the dynamic large voltage fluctuations of the DC bus can be quickly suppressed, ensuring the stability of the DC bus voltage.

[0019] In the preferred technical solution of the above-mentioned DC interconnected charging and swapping system, the dynamic braking circuit includes a power electronic switch, a braking resistor, and a freewheeling diode, wherein the power electronic switch is connected in series with the braking resistor, the freewheeling diode is connected in parallel with the braking resistor, and the freewheeling direction of the freewheeling diode is from the negative bus to the positive bus on the DC bus.

[0020] In the preferred technical solution of the above-mentioned DC interconnected charging and swapping system, a capacitor bank is also provided on the DC bus.

[0021] The installation of capacitor banks can increase the stability of DC bus voltage, especially in the event of power surges caused by grid or DC side equipment failures.

[0022] In the preferred embodiment of the above-mentioned DC interconnected charging and swapping system, the AC / DC converter is a converter with bidirectional short-circuit current interruption capability, and a third fuse is provided between the AC / DC converter and the DC bus, the fusing time of the third fuse being not less than 10ms; or the AC / DC converter is a converter with unidirectional short-circuit current interruption capability, and a fourth fuse is provided between the AC / DC converter and the DC bus on the side without current interruption capability, the fusing time of the fourth fuse being not greater than 5ms.

[0023] By configuring an AC / DC converter with bidirectional short-circuit current interruption capability, since this type of converter can quickly turn off through semiconductors in the event of a short circuit, only a third fuse with a fusing time of not less than 10ms is required. However, for AC / DC converters with only unidirectional short-circuit current interruption capability, fuses with millisecond-level response are needed to ensure the rapid short-circuit protection of the system. Therefore, a millisecond-level (not greater than 5ms) ultra-fast fuse must be equipped on the side that cannot interrupt the current to ensure that the fault zone can achieve millisecond-level isolation, preventing fault propagation and ensuring the normal operation of other zones in the system. Attached Figure Description

[0024] The preferred embodiments of this application will now be described with reference to the accompanying drawings.

[0025] Figure 1 This is a system diagram of the DC interconnected charging and swapping system of this application.

[0026] Figure 2 This is a circuit diagram of the dynamic braking circuit of the DC interconnected charging and swapping system of this application.

[0027] Figure 3 This is a circuit diagram of the partition connection device of the DC interconnected charging and swapping system of this application.

[0028] List of reference numerals 1. DC Zone; 11. DC Bus; 121. AC / DC Converter; 122. First DC / DC Converter; 123. Third DC / DC Converter; 131. Charging / Swapping Equipment; 132. Energy Storage Device; 133. Photovoltaic Power Generation Device; 141. First Fuse; 142. Second Fuse; 144. Fourth Fuse; 15. Dynamic Braking Circuit; 151. Power Electronic Switch; 152. Braking Resistor; 153. Freewheeling Diode; 16. Capacitor Bank; 2. Zone Connection Device; 21. DC Switch; 22. Inrush Current Suppression Circuit; 221. Current Limiting Resistor; 222. Bypass Switch; 23. Second DC / DC Converter; 24. Metering Sensor; 3. AC Power Grid. Detailed Implementation

[0029] Preferred embodiments of this application will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.

[0030] It should be noted that in the description of this application, the terms "left," "right," etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is merely for ease of description and does not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, it should not be construed as a limitation of this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Additionally, in the description of this application, "a plurality of" refers to at least two.

[0031] First refer to Figure 1 This paper provides a brief introduction to the DC interconnected charging and swapping system of this application.

[0032] like Figure 1As shown, in order to solve the problems of high cost and limited peak-hour capacity of existing charging and swapping stations when configuring energy storage systems and photovoltaic power generation systems, the DC interconnected charging and swapping system of this application includes: at least two DC zones 1, each DC zone 1 including a DC bus 11, an AC / DC converter 121, a DC / DC converter and charging and swapping equipment 131, the DC bus 11 being connected to the AC grid 3 through the AC / DC converter 121, and the charging and swapping equipment 131 being connected to the DC bus 11 through the DC / DC converter; and a zone connection device 2, wherein the DC bus 11 of each DC zone 1 is connected to the DC bus 11 of at least another DC zone 1 through the zone connection device 2, and the zone connection device 2 is capable of controlling the on / off connection between at least two interconnected DC buses 11.

[0033] In one possible implementation, at least two DC zones 1 independently obtain electrical energy from the AC power grid 3 for the operation of the charging and swapping equipment 131. When one DC zone 1 has a higher power demand than the other, the DC buses 11 of the two DC zones 1 can be connected through the zone connection device 2 between them to achieve capacity sharing, thereby supplementing the power of one DC zone 1 to the other DC zone 1 through the zone connection device 2.

[0034] By adopting the above technical solution, this application can fully utilize the spatiotemporal complementarity of the loads at various power stations, smooth load fluctuations, achieve capacity sharing, and significantly reduce the investment in power distribution capacity expansion or the installation of energy storage devices 132. Specifically, due to differences in scenarios and user habits, electric vehicle charging facilities such as battery swapping stations, public charging piles, and home charging piles naturally exhibit spatiotemporal differences in charging and swapping equipment 131. For example, home charging piles typically concentrate on charging during off-peak hours at night, public charging piles usually have two distinct peak periods: midday and early morning. Battery swapping stations, due to different peak-shaving charging strategies and user types, exhibit different types of load characteristics. Overall, battery swapping stations, public charging piles, and home charging piles have complementary spatiotemporal characteristics. Compared with traditional charging and swapping equipment 131 being connected to the power grid separately, this application effectively utilizes this complementary characteristic by connecting the DC buses 11 under different DC zones 1 through zoned connections. This enables capacity scheduling among multiple DC buses 11, improves the carrying capacity and service capacity of electric vehicles, and reduces the number of energy storage devices 132 and photovoltaic power generation devices 133, avoiding redundant investment in energy storage.

[0035] The following is combined Figures 1 to 3 This paper provides a detailed description of one specific implementation of the DC interconnected charging and swapping system of this application.

[0036] like Figures 1 to 3As shown, in one specific embodiment, the DC interconnected charging and swapping system includes two DC zones 1 and one zone connection device 2. Each DC zone 1 includes a DC bus 11, an AC / DC converter 121, a first DC / DC converter 122, charging and swapping equipment 131, a dynamic braking circuit 15, and a capacitor bank 16. The difference between the two is that... Figure 1 The left-hand DC partition 1 is equipped with an energy storage device 132. Figure 1 The DC partition 1 on the right is equipped with a photovoltaic power generation device 133.

[0037] Specifically, each DC bus 11 of DC zone 1 is connected to AC grid 3 through two AC / DC converters 121, with a transformer installed between the AC / DC converters 121 and AC grid 3. The control objective of the AC / DC converters 121 is to maintain the corresponding DC bus 11 within a certain range. Multiple AC / DC converters 121 achieve power balance or power distribution among the converters through DC bus 11 voltage droop control. In this application, the AC / DC converters 121 are unidirectional or bidirectional AC / DC converters 121, and have unidirectional short-circuit current interruption capability. For example, a conventional two-level inverter topology has AC side short-circuit current interruption capability, but cannot interrupt DC side short-circuit current. Therefore, a fourth fuse 144 is additionally installed between the side of the AC / DC converter 121 that does not have current interruption capability and the DC bus 11. The melting time of the fourth fuse 144 is no more than 5ms. In one specific embodiment, the fourth fuse 144 is a millisecond-level ultra-fast fuse, such as a fire fuse with a fusing time of 1 to 3 ms.

[0038] For the AC / DC converter 121, which only has the ability to cut off short-circuit current in one direction, a fuse with a response of milliseconds is required to ensure the fast short-circuit protection of the system. Therefore, a millisecond-level (no more than 5ms) ultra-fast fuse is required on the side that cannot cut off the current to ensure that the fault zone can be isolated at the millisecond level, the fault will not spread, and it will not affect the normal operation of other zones of the system.

[0039] In other alternative embodiments, the AC / DC converter 121 can also be a unidirectional or bidirectional converter with bidirectional short-circuit current interruption capability, such as a conventional back-to-back converter. In this case, a third fuse is additionally provided between the AC / DC converter 121 and the DC bus 11. The fusing time of the third fuse is not less than 10 ms, for example, a fast-acting fuse based on the I²t principle, whose operating time typically requires tens of milliseconds. By providing an AC / DC converter 121 with bidirectional short-circuit current interruption capability, since this converter can quickly turn off through semiconductors when a short circuit occurs, only a third fuse with a fusing time of not less than 10 ms needs to be configured.

[0040] Furthermore, the specific implementation of the aforementioned ultra-fast fuse is not limited to fire protection; those skilled in the art can substitute it, as long as the selected fuse's breaking time is no greater than 5ms.

[0041] Continue to refer to Figure 1 Each DC partition 1 has a charging / swapping device 131 connected to the DC bus 11 via four first DC / DC converters 122. In this application, the charging / swapping device 131 can be a charging pile, a battery swapping station, etc. The left-side DC partition 1 also has an energy storage device 132, which is connected to the DC bus 11 via a first DC / DC converter 122. The right-side DC partition 1 also has a photovoltaic power generation device 133, which is connected to the DC bus 11 via a third DC / DC converter 123.

[0042] The first DC / DC converter 122 can be a unidirectional or bidirectional DC / DC converter with bidirectional short-circuit current interruption capability, such as an H-bridge topology or a common high-frequency isolated DC / DC module. A first fuse 141 is provided between the first DC / DC converter 122 and the DC bus 11. The fusing time of the first fuse 141 is not less than 10ms. For example, a fast-acting fuse based on the I²t principle typically requires tens of milliseconds to operate. By setting a first DC / DC converter 122 with bidirectional short-circuit current interruption capability, since this converter can quickly turn off in the event of a short circuit, only a first fuse 141 with a fusing time of not less than 10ms is needed.

[0043] The third DC / DC converter 123 can also be a unidirectional or bidirectional DC / DC converter with unidirectional short-circuit current interruption capability, such as a conventional boost topology, which can interrupt the short-circuit current on the low-voltage side but cannot interrupt the short-circuit current on the high-voltage side. Therefore, a second fuse 142 is provided between the side of the DC / DC converter that lacks current interruption capability and the DC bus 11. The fusing time of the second fuse 142 is no greater than 5ms. In one specific embodiment, the second fuse 142 is a millisecond-level ultra-fast fuse, such as a fire fuse with a fusing time of 1~3ms.

[0044] For DC / DC converters with only unidirectional short-circuit current interruption capability, unlike traditional AC systems where short-circuit current can be protected by conventional AC circuit breakers and fuses with mature protection parameter setting methods, DC interconnected systems lack inductive reactance. When a short-circuit fault occurs, the system's short-circuit impedance is low, resulting in a very high steady-state short-circuit current with a rapid rise time. The fault range is much larger than in AC interconnected systems, easily causing fault propagation and system shutdown. In particular, since the short-circuit current in DC systems is DC and has no zero-crossing point, traditional DC circuit breakers are ineffective at interrupting DC arcs. Traditional I²t-based fast-acting fuses with a response time of tens to hundreds of milliseconds cannot achieve rapid fault isolation and prevent propagation; a single short circuit can cause all connected DC zones 1 to shut down, significantly impacting operations. Using new power electronics-based DC circuit breakers would be prohibitively expensive, and traditional fuses, with their slow response times (tens of milliseconds or more), also fail to meet the requirements for fast system protection. Therefore, a millisecond-level (no more than 5ms) ultra-fast fuse must be equipped on the side that cannot interrupt the current to ensure that the faulty section can be isolated at the millisecond level, preventing the fault from spreading and affecting the normal operation of other sections of the system. Of course, the specific implementation of the above-mentioned ultra-fast fuse is not limited to fire fuses; those skilled in the art can replace it, as long as the selected fuse's fusing time is no more than 5ms.

[0045] In other alternative embodiments, the DC / DC converter between the charging / swapping device 131 and the DC bus 11 can be configured as a DC / DC converter with only unidirectional short-circuit current interruption capability, and a fuse with a fusing time of no more than 5ms can be configured between the DC / DC converter and the DC bus 11. Similarly, the DC / DC converter between the energy storage device 132 and the DC bus 11 can also be replaced with a DC / DC converter with only unidirectional short-circuit current interruption capability, and a fuse with a fusing time of no more than 5ms can be configured. Similarly, the DC / DC converter between the photovoltaic power generation device 133 and the DC bus 11 can be configured as a DC / DC converter with bidirectional short-circuit current interruption capability, and a conventional fuse with a fusing time of no less than 10ms can be configured between the DC / DC converter and the DC bus 11.

[0046] By setting up energy storage device 132 and / or photovoltaic power generation device 133 in DC partition 1, the energy conversion stages are fewer compared to traditional AC coupling methods, and the system has higher efficiency and response speed in scenarios with limited AC penetration. Of course, the setting of energy storage device 132 and photovoltaic power generation device 133 is not mandatory. Those skilled in the art can choose whether to set up the above two devices, as well as the specific number and location of the above two devices when setting them up.

[0047] Reference Figure 1 and Figure 2A dynamic braking circuit 15 is also provided on the DC bus 11. The dynamic braking circuit 15 is configured to stabilize the voltage of the DC bus 11. Specifically, the dynamic braking circuit 15 includes a power electronic switch 151, a braking resistor 152, and a freewheeling diode 153. The power electronic switch 151 is connected in series with the braking resistor 152, and the freewheeling diode 153 is connected in parallel with the braking resistor 152. The freewheeling direction of the freewheeling diode 153 is from the negative bus to the positive bus on the DC bus.

[0048] For sudden faults in charging systems of charging piles or battery swapping stations, such as a sudden stop of charging at the charging terminal due to a fault during high-power charging (charger tripping), existing technologies typically control these faults using multiple distributed low-power AC / DC devices. However, the DC voltage control bandwidth is low, and the total capacity of the DC bus 11 is limited. Therefore, the voltage of the partitioned DC bus 11 can exceed the normal voltage range within milliseconds, even affecting the normal operation of the charging and swapping equipment 131 in adjacent DC partitions 1 on the bus. To address this, this application introduces a dynamic braking circuit 15 (where the braking resistor 152 can withstand at least hundreds of milliseconds of partition rated power, typically 500 milliseconds to 1 second) to replace the slow discharge circuit in traditional charging modules, ensuring that large dynamic voltage fluctuations in the DC bus 11 can be quickly suppressed. Furthermore, unlike typical discharge modules, the dynamic braking circuit 15 in this application uses fast IGBTs or MOSFETs as power electronic switches 151, driven by PWM rather than IO to achieve microsecond-level response and DC bus 11 voltage regulation. Meanwhile, the braking resistor 152 and the freewheeling diode 153 are connected in anti-parallel to meet the freewheeling requirements of the resistor during fast switching of IGBT or MOSFET.

[0049] By setting up the dynamic braking circuit 15, an effective response can be made to the frequent fault modes (sudden stop during charging) during electric vehicle recharging, so that the dynamic large voltage fluctuations of the DC bus 11 can be quickly suppressed, ensuring the voltage stability of the DC bus 11. Of course, the setting of the dynamic vehicle-related circuit is only an example, and those skilled in the art can choose to omit this circuit, but correspondingly, it will not be conducive to maintaining the stability of the DC bus 11. In other embodiments, the specific circuit structure of the dynamic braking circuit 15 can be adjusted by those skilled in the art, as long as the adjusted circuit can effectively suppress the voltage fluctuations of the DC bus when the charging and swapping equipment 131 fails.

[0050] Continue to refer to Figure 1A capacitor bank 16 is also provided on the DC bus 11. The arrangement of the capacitor bank 16 is not limited in this application; any commonly used capacitor bank 16 in the art can be applied. The purpose of providing the capacitor bank 16 is to increase the voltage stability of the DC bus 11, especially in cases where power surges are caused by faults in the power grid, DC-side loads (charging piles and battery swapping stations), energy storage device 132, and photovoltaic power generation device 133. Of course, the provision of the capacitor bank 16 is not mandatory; those skilled in the art can choose whether to provide it based on specific needs.

[0051] Reference Figure 1 and Figure 3 The partition connection device 2 includes a DC switch 21, an inrush current suppression circuit 22, a second DC / DC converter 23, and a metering sensor 24. (Refer to...) Figure 3 As shown, a DC switch 21 is installed on each of the DC bus 11 of the two interconnected DC partitions 1. A second DC / DC converter 23 is installed between the two DC switches 21. A metering sensor 24 is installed on each side of the second DC / DC converter 23. A first fuse 141 is installed between each metering sensor 24 and the DC switch 21 on the same side. An inrush current suppression circuit 22 is installed between the first fuse 141 on the right side and the DC switch 21 on the right side.

[0052] The aforementioned second DC / DC converter 23 can be a unidirectional or bidirectional DC / DC converter. For example, for DC partition 1 with ample circuit capacity, a unidirectional DC / DC converter can be used to supply power to DC partition 1 with limited capacity when needed, without requiring other DC partitions 1 to supply power to this partition. For partitions with limited capacity and inconsistent voltages, a bidirectional DC / DC converter is preferable to achieve capacity complementarity between DC partitions 1. Furthermore, the second DC / DC converter 23 has bidirectional short-circuit current interruption capability. Therefore, a first fuse 141, i.e., a conventional fast-acting fuse with a fusing time of not less than 10ms, is installed between its two sides and the corresponding DC bus 11. The specific installation method can be referred to above and will not be repeated here. Of course, if the second DC / DC converter 23 is configured to have unidirectional short-circuit current interruption capability, a super-fast fuse with a fusing time of not more than 5ms needs to be installed between the side without short-circuit interruption capability and the DC bus 11. By setting the second DC / DC converter 23, two DC partitions 1 with different voltages can be connected, improving the system's applicability.

[0053] In this application, the metering sensor 24 can measure at least one of voltage, current, and electrical energy. In one specific embodiment, the metering sensor 24 can simultaneously measure voltage, current, and electrical energy. Furthermore, the two metering sensors 24 can be configured as sensors with identical functions or with different functions. For example, when using a unidirectional DC / DC converter, a sensor with electrical energy measurement can be provided only on one side.

[0054] The inrush current suppression circuit 22 includes a current-limiting resistor 221 and a bypass switch 222 connected in parallel. When the two DC bus 1s are first connected, they are linked by the current-limiting resistor 221, which dissipates excess voltage. When the voltages of the two bus 1s approach the same level (e.g., within 10V), the bypass switch 222 closes, connecting the DC buses 11 of the two bus 1s. The inrush current suppression circuit 22 limits the large inrush current generated at the moment of connection of the DC bus 11, protecting the DC bus 11 and ensuring system reliability.

[0055] It should be noted that the specific configuration of the partition connection device 2 is not fixed and can be adjusted by those skilled in the art based on specific application scenarios. For example, for partitions with consistent voltage levels, the partition connection device 2 can be simplified to a combination of a DC switch 21, a fuse, and an inrush current suppression circuit 22, omitting the second DC / DC converter 23. Furthermore, the specific circuit structure of the inrush current suppression circuit 22 can be modified by those skilled in the art to other commonly used circuit forms. Moreover, the inclusion of a fuse is not mandatory; for example, if the DC switch 21 integrates a fuse function, the fuse can be omitted.

[0056] It should also be noted that although the above implementation is described with two DC partitions 1 as an example, this is only an example. In other alternative implementations, those skilled in the art can connect more DC partitions 1 through the partition connection device 2, and each DC partition 1 can be connected to only one DC partition 1 of other DC partitions 1 through the partition connection device 2, or it can be connected to multiple DC partitions 1 of other DC partitions 1.

[0057] Furthermore, the descriptions of quantities in the above embodiments are all exemplary (e.g., the number of AC / DC converters 121, the number of DC / DC converters, etc.), and those skilled in the art can adjust them.

[0058] Of course, the alternative implementation methods mentioned above, as well as the alternative implementation methods and preferred implementation methods, can be used in combination to create new implementation methods that are suitable for more specific application scenarios.

[0059] Those skilled in the art will understand that although some embodiments described herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, any of the claimed embodiments in the claims of this application can be used in any combination.

[0060] The technical solutions of this application have been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A DC interconnected charging and swapping system, characterized in that, include: At least two DC zones, each of which includes a DC bus, an AC / DC converter, a DC / DC converter, and charging / swapping equipment. The DC bus is connected to the AC power grid through the AC / DC converter, and the charging / swapping equipment is connected to the DC bus through the DC / DC converter. A partition connection device, wherein the DC bus of each DC partition is connected to the DC bus of at least another DC partition through the partition connection device, and the partition connection device is capable of controlling the on / off state between at least two DC buses connected to each other.

2. The DC interconnected charging and swapping system according to claim 1, characterized in that, The partition connection device includes a DC switch and an inrush current suppression circuit.

3. The DC interconnected charging and swapping system according to claim 2, characterized in that, The inrush suppression circuit includes current-limiting resistors and bypass switches connected in parallel.

4. The DC interconnected charging and swapping system according to claim 2, characterized in that, The partition connection device also includes a DC / DC converter, which is disposed between two DC buses that are connected to each other.

5. The DC interconnected charging and swapping system according to claim 1, characterized in that, At least one of the DC zones is further provided with an energy storage device and / or a photovoltaic power generation device, which is connected to the DC bus via a DC / DC converter.

6. The DC interconnected charging and swapping system according to claim 1, 4, or 5, characterized in that, The DC / DC converter is a converter with bidirectional short-circuit current interruption capability, and a first fuse is provided between the DC / DC converter and the DC bus, the fusing time of the first fuse being not less than 10ms; or The DC / DC converter is a converter with unidirectional short-circuit current interruption capability, and a second fuse is provided between the DC / DC converter and the DC bus on the side without current interruption capability, and the melting time of the second fuse is no more than 5ms.

7. The DC interconnected charging and swapping system according to claim 1, characterized in that, A dynamic braking circuit is also provided on the DC bus, and the dynamic braking circuit is configured to stabilize the voltage of the DC bus.

8. The DC interconnected charging and swapping system according to claim 7, characterized in that, The dynamic braking circuit includes a power electronic switch, a braking resistor, and a freewheeling diode, wherein the power electronic switch is connected in series with the braking resistor, the freewheeling diode is connected in parallel with the braking resistor, and the freewheeling direction of the freewheeling diode is from the negative bus to the positive bus on the DC bus.

9. The DC interconnected charging and swapping system according to claim 1, characterized in that, A capacitor bank is also installed on the DC bus.

10. The DC interconnected charging and swapping system according to claim 1, characterized in that, The AC / DC converter is a converter with bidirectional short-circuit current interruption capability, and a third fuse is provided between the AC / DC converter and the DC bus, the fusing time of the third fuse being not less than 10ms; or The AC / DC converter is a converter with unidirectional short-circuit current interruption capability, and a fourth fuse is provided between the AC / DC converter and the DC bus on the side without current interruption capability, and the melting time of the fourth fuse is no more than 5ms.

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