Split type direct current charger power distribution unit

Abstract

The application belongs to the technical field of direct current charging of electric vehicles, and discloses a split type direct current charger power distribution unit, which comprises positive and negative power distribution rings arranged symmetrically, each charging module is connected to a node in the ring through a contactor, and each charging terminal is connected to the node of one or more rings through a contactor. By controlling the on-off of the corresponding contactor, the power of any charging module can be dynamically and flexibly distributed to any charging terminal. The application adopts a double-ring or even multi-ring topology, divides large current, controls single-loop current at a low level, thereby allowing the use of a contactor and copper bar with smaller rated current and lower cost, significantly reducing system cost and heat. The structure supports the power superposition of the charging terminal by taking power from multiple points on a single ring, and facilitates the access of energy storage equipment, and has the advantages of flexible deployment, fast response speed and high reliability.

Description

Technical Field

[0001] This invention relates to the field of DC charging technology for electric vehicles, and more specifically, to a split-type DC charger power distribution unit. Background Technology

[0002] With the rapid popularization of electric vehicles, the demand for high-power DC fast charging is increasing. Split-type DC chargers have become the mainstream choice for charging stations due to their advantages of shared "power pool" and flexible allocation. The core of the unit is the power distribution unit, which is responsible for distributing the output power of multiple centrally located charging modules (AC / DC converters) to multiple decentralized charging terminals (charging guns) as needed.

[0003] Currently, the main power distribution solutions on the market are as follows:

[0004] 1. Centralized Contactor Matrix Topology: All charging modules are connected in parallel to a common DC bus, and each charging terminal is connected to this bus through an independent set of high-power contactors. This solution is technically mature, but has significant drawbacks: each terminal requires a high-cost, high-current contactor (including pre-charge and discharge circuits), resulting in a large number of contactors in the entire PDU, high cost, and bulky cabinet. For example, a system supporting 8 terminals may require 64 to 128 high-current contactors. Furthermore, contactors have a limited mechanical lifespan; frequent dynamic power scheduling shortens their lifespan, and the smallest granularity of power allocation is limited by the power of a single charging module, making finer-grained allocation impossible.

[0005] 2. Hierarchical (Star) Topology: This introduces a two-level distribution using "Level 1 PDU" and "Level 2 PDU". While this reduces the current rating of individual contactors to some extent, it increases the length of the power transmission path and the number of connection points, leading to accumulated conduction losses (voltage drop) and reduced system efficiency. More importantly, the Level 2 PDU becomes a critical point; a failure there will paralyze all charging terminals connected to it, resulting in high reliability risks. The control software also becomes more complex due to the need to manage the switching states of both levels.

[0006] 3. Secondary Distribution Topology Based on DC / DC Converters: A DC / DC converter is added before each charging terminal to achieve precise and flexible voltage conversion and power regulation. However, DC / DC converters themselves are extremely expensive and introduce additional power losses (typically with an efficiency of 96%-97%). When transmitting high power, these losses significantly increase operating electricity costs and generate a large amount of heat, worsening heat dissipation conditions. Furthermore, their dynamic response speed is limited by the circuitry and control loop.

[0007] 4. Solid-state switch matrix topology: This topology completely replaces mechanical contactors with fully controllable semiconductor devices such as IGBTs and SiC MOSFETs. It offers fast switching speeds, no electric arcs, and long lifespans, making it the future direction. However, currently, semiconductor devices are extremely expensive, have high conduction losses, and require complex drive, protection, and heat dissipation systems, making the overall cost prohibitive for commercial charging station scenarios.

[0008] In summary, existing technologies struggle to achieve a good balance between cost, efficiency, flexibility, reliability, and response speed. Therefore, there is an urgent need for an innovative power distribution unit design that can significantly reduce hardware costs, simplify control, and improve system reliability and energy efficiency while meeting the flexible deployment requirements of split-type chargers. Summary of the Invention

[0009] To overcome the aforementioned deficiencies of the prior art and to achieve the above objectives, the present invention provides the following technical solution:

[0010] A split-type DC charger power distribution unit, characterized in that it is applied to a main unit cabinet and a charging module disposed within the main unit cabinet, the power distribution unit comprising:

[0011] A positive power distribution ring and a negative power distribution ring, wherein the positive power distribution ring and the negative power distribution ring have the same structure and are symmetrically arranged;

[0012] The positive power distribution ring is formed by sequentially connecting multiple nodes of the connecting contactor to form a ring topology;

[0013] The DC positive output terminal of each charging module is connected to a node of the positive power ring via a connection contactor, and the DC positive input terminal of each charging terminal is connected to one or more nodes of the positive power ring via at least one charging gun connection contactor.

[0014] The structure and connection relationship of the negative power distribution ring correspond to that of the positive power distribution ring, and are used to connect the DC negative output terminal of the charging module to the DC negative input terminal of the charging terminal.

[0015] By controlling the on / off state of the module access contactor, the inter-ring connection contactor, and the charging gun connection contactor, any one or more of the charging modules can be assigned to any one of the charging terminals to form a charging circuit.

[0016] Furthermore, it also includes an energy storage connection port for connecting an energy storage battery pack;

[0017] The DC positive terminal of the energy storage connection port is connected to a node of the positive power distribution ring via an energy storage connection contactor, and the DC negative terminal of the energy storage connection port is connected to a node of the negative power distribution ring via a corresponding contactor.

[0018] By controlling the on / off state of the energy storage connection contactor, the energy storage battery pack is connected to the power distribution unit so that the energy storage battery pack can be charged by the charging module or discharged to the charging terminal by the energy storage battery pack.

[0019] Furthermore, each of the positive power rings and each of the negative power rings is composed of four nodes connected sequentially to form a single-ring structure, and each single-ring structure is also provided with an intra-ring adjustment contactor for adjusting the power distribution path within the ring.

[0020] Furthermore, the DC positive and negative input terminals of a single charging terminal are respectively connected to two different nodes on the same power loop through two charging gun connection contactors to achieve power superposition.

[0021] Furthermore, the rated current of the charging gun connection contactor, the module access contactor, the inter-ring connection contactor, and the intra-ring adjustment contactor is no greater than 300A.

[0022] Furthermore, the power distribution unit is applied to a charging module with a rated power of 720kW, wherein:

[0023] The positive power distribution ring and the negative power distribution ring each include two positive power rings and two negative power rings;

[0024] The number of charging modules is multiple, with a total power of 720kW;

[0025] The charging terminal includes a liquid-cooled charging gun with a rated current of 600A and a regular charging gun with a rated current of 250A.

[0026] The power distribution unit contains a total of 48 contactors, all of which have a rated current of 300A.

[0027] Furthermore, the energy storage connection port supports connection to at least one energy storage battery pack with a rated power of 261kW.

[0028] The technical effects and advantages of the split-type DC charger power distribution unit of this invention are as follows:

[0029] 1. Significantly reduced cost: Through multi-loop current shunting design, the circuit operating current is controlled at a low level (e.g., below 300A), enabling the system to use a large number of small-sized, low-cost connecting contactors and small-sized copper busbars;

[0030] 2. High flexibility in power allocation: The dual-ring structure provides redundant paths. When a single ring fails or some nodes are occupied, the power can be allocated using another ring through the inter-ring contactor. The charging terminal can draw power from multiple points on a single ring to achieve power multiplication, meeting the needs of vehicles with different power levels. The seamless access of energy storage devices further enhances the system's energy scheduling flexibility.

[0031] 3. Simple and efficient control algorithm: The positions of power modules and charging terminals in the topology are clear. When the software scheduling algorithm allocates power modules to charging requests, the pathfinding logic is simple and intuitive. It usually only needs to determine which ring to use and which available node in the ring. The maximum pathfinding depth is only two levels, which greatly reduces software complexity and decision time.

[0032] 4. Fast system response speed: Due to the reduced number of contactors used, and the fact that they are all low-current contactors, their operating time (closing / releasing) is relatively shorter, and the control logic is simplified, which improves the system's response speed to power dispatch commands.

[0033] 5. High operating efficiency and low heat generation: The low conduction loss caused by the low current directly reduces the heat generated by useless work, improves the energy conversion efficiency of the entire charging system, and the less heat generation also reduces the requirements for the heat dissipation system, improves the long-term working reliability of electronic components, and extends the system life.

[0034] 6. Compact structure and easy deployment: Miniaturized contactors and thin copper busbars make the internal layout of the power distribution unit cabinet more compact and reduce the overall size, which is conducive to deployment and installation in charging stations where land resources are scarce. Attached Figure Description

[0035] Figure 1 This is a topology diagram of the power distribution unit of the present invention;

[0036] Figure 2 This is a system diagram of the power distribution unit of the present invention;

[0037] Figure 3 This is a schematic diagram of the power distribution principle of the power distribution unit of the present invention;

[0038] Figure 4 This is a contactor connection assembly diagram of the present invention. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] like Figures 1-4 The power distribution unit shown is a split-type DC charger. It is used in a charging system that includes a main cabinet, multiple charging modules and multiple charging terminals installed in the main cabinet. The core of the power distribution unit is its unique ring topology, which specifically includes a symmetrically arranged positive power distribution ring and a negative power distribution ring.

[0041] The positive power distribution ring consists of multiple nodes connected sequentially via connecting contactors to form a closed-loop circuit. The DC positive output terminal of each charging module is connected to a node of a positive power ring via a module access contactor. Similarly, the DC positive input terminal of each charging terminal is connected to one or more nodes of the positive power ring via at least one charging gun connecting contactor.

[0042] The negative power distribution ring is structurally symmetrical to and electrically isolated from the positive power distribution ring, and is used to connect the DC negative output terminal of all charging modules and the DC negative input terminal of all charging terminals in the same way.

[0043] Through a control unit, such as a PLC or embedded controller, the connection and disconnection of each module connection contactor, inter-ring connection contactor, and charging gun connection contactor can be precisely controlled. This allows for the establishment of an electrical path from any one or more charging modules to any designated charging terminal in a complex ring network, thereby achieving flexible and dynamic power distribution.

[0044] The power distribution unit can also integrate an energy storage interface. The energy storage battery pack can be connected to the nodes of the positive and negative power loops through the energy storage connection contactor. This allows the system to not only distribute the power of the charging module to the charging terminal to charge electric vehicles, but also to use the charging module to charge the energy storage battery pack when the grid electricity price is low. When the electricity price is high or the grid power is insufficient, the power of the energy storage battery pack can be supplied to the charging terminal in reverse through the power distribution loop to achieve peak shaving and valley filling and improve the economic benefits of the charging station.

[0045] Each power ring consists of four nodes, and an internal distribution contactor is also set up within the ring to provide alternative current paths when the internal path is occupied, increasing the flexibility of distribution. For high-power charging terminals (such as 600A liquid-cooled guns), their positive and negative terminals can be connected to two different nodes on the same power ring, which is equivalent to drawing power from two points on the ring in parallel, thereby achieving current superposition to meet the high current demand, while each branch only needs to bear half of the current.

[0046] By using a dual-ring or even multi-ring structure, a large current (such as 600A) that might otherwise be concentrated on a single path can be distributed into multiple parallel ring branches. For example, for a 600A charging demand, the current can be controlled to be supplied by two 300A parallel loops. This limits the current flowing through each individual contactor and each copper busbar to a lower level (e.g., no more than 300A). Therefore, DC contactors with smaller rated current, smaller size, and lower price, as well as copper busbars with smaller cross-sectional areas, can be selected, resulting in significant savings in component costs, cabinet size, and wiring costs. At the same time, lower current means lower conduction losses (I²R) and heat generation, improving system energy efficiency and reliability.

[0047] Example: A power distribution unit applied to a 720kW split-type DC charger.

[0048] Reference Figure 1 and Figure 2 The system includes a main cabinet, which houses 18 40kW charging modules (total power 720kW). The main cabinet is externally connected to two 600A liquid-cooled charging guns and ten 250A ordinary charging guns as charging terminals. In addition, the system is also designed to connect to a 261kW energy storage battery pack.

[0049] like Figure 2 As shown in the figure, the topology of a single positive and negative pole of the power distribution unit is shown. The entire power distribution unit consists of two rings, one on the left and one on the right, which are the positive and negative poles respectively. M1-M18 are 18 40kW charging modules connected to the circuit. The nodes are connected to each other through DC contactors (not shown in the figure). Nodes 1 and 9 are connected in parallel. Nodes 1 and 9 are connected to two 600A liquid-cooled guns. Nodes 2, 3, 4, 5, 6, 7, 8, 10, 11, and 12 are connected to 10 250A charging guns respectively.

[0050] like Figure 3As shown in the figure, this is a system diagram of the power distribution unit. The main topology of the entire power distribution unit consists of two ring circuits connected to guns 1-7 and guns 8-14. Modules UR1-2 corresponding to gun 1 are bridged with modules UR6 corresponding to gun 4 and UR7 corresponding to gun 5 through DC contactors 1KZ8 / 2KZ8 and 1KZ9 / 2KZ9. Modules UR3-4 corresponding to gun 2 are directly connected and bridged with modules UR7 corresponding to gun 5 and UR8 corresponding to gun 6 through DC contactors 1KZ10 / 2KZ10 and 1KZ11 / 2KZ11. Modules UR10-11 corresponding to gun 8 are directly connected through DC contactor 1KZ2. 0 / 2KZ20 and 1KZ21 / 2KZ21 are bridged with the corresponding modules UR15 of gun 11 and UR16 of gun 12. The direct-connect modules UR12~13 of gun 9 are bridged with the corresponding modules UR16 of gun 12 and UR17 of gun 13 through DC contactors 1KZ22 / 2KZ22 and 1KZ23 / 2KZ23, thus completing the connection of the entire power distribution unit. The #1 energy storage cabinet is connected to the gun 1 circuit through 1#ESS+ / 1#ESS-, and the #2 energy storage cabinet is connected to the gun 8 circuit through 2#ESS+ / 2#ESS-, thus completing the process of energy storage participating in power distribution.

[0051] All contactors are selected as 300A, totaling 48 DC contactors; the module optimization path is: clockwise search within the loop, counterclockwise search within the loop, and path search. When there is a 600A liquid-cooled supercharging requirement, the two loops need to be connected in parallel for output, and the output current of a single loop is limited to 300A; the charging module allocation adopts the 2, 2, 1, 1, 1, 1, 1 method; in this way, the path finding process of the entire power distribution unit is completed.

[0052] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A split-type DC charger power distribution unit, characterized in that, The power distribution unit, which is applied to a main unit cabinet and a charging module disposed within the main unit cabinet, includes: A positive power distribution ring and a negative power distribution ring, wherein the positive power distribution ring and the negative power distribution ring have the same structure and are symmetrically arranged; The positive power distribution ring is formed by sequentially connecting multiple nodes of the connecting contactor to form a ring topology; The DC positive output terminal of each charging module is connected to a node of the positive power ring via a connection contactor, and the DC positive input terminal of each charging terminal is connected to one or more nodes of the positive power ring via at least one charging gun connection contactor. The structure and connection relationship of the negative power distribution ring correspond to that of the positive power distribution ring, and are used to connect the DC negative output terminal of the charging module to the DC negative input terminal of the charging terminal. By controlling the on / off state of the module access contactor, the inter-ring connection contactor, and the charging gun connection contactor, any one or more of the charging modules can be assigned to any one of the charging terminals to form a charging circuit.

2. The split-type DC charger power distribution unit according to claim 1, characterized in that, It also includes an energy storage connection port for connecting an energy storage battery pack; The DC positive terminal of the energy storage connection port is connected to a node of the positive power distribution ring via an energy storage connection contactor, and the DC negative terminal of the energy storage connection port is connected to a node of the negative power distribution ring via a corresponding contactor. By controlling the on / off state of the energy storage connection contactor, the energy storage battery pack is connected to the power distribution unit so that the energy storage battery pack can be charged by the charging module or discharged to the charging terminal by the energy storage battery pack.

3. The split-type DC charger power distribution unit according to claim 1 or 2, characterized in that, Each of the positive power rings and each of the negative power rings consists of four nodes connected sequentially to form a single-ring structure. Each single-ring structure is also equipped with an intra-ring adjustment contactor for adjusting the power distribution path within the ring.

4. The split-type DC charger power distribution unit according to claim 3, characterized in that, The positive and negative DC input terminals of a single charging terminal are respectively connected to two different nodes on the same power loop through two charging gun connection contactors to achieve power superposition.

5. The split-type DC charger power distribution unit according to claim 4, characterized in that, The rated current of the charging gun connection contactor, the module access contactor, the inter-ring connection contactor, and the intra-ring adjustment contactor is no greater than 300A.

6. The split-type DC charger power distribution unit according to claim 1, characterized in that, The power distribution unit is applied to a charging module with a rated power of 720kW, wherein: The positive power distribution ring and the negative power distribution ring each include two positive power rings and two negative power rings; The number of charging modules is multiple, with a total power of 720kW; The charging terminal includes a liquid-cooled charging gun with a rated current of 600A and a regular charging gun with a rated current of 250A. The power distribution unit contains a total of 48 contactors, all of which have a rated current of 300A.

7. The split-type DC charger power distribution unit according to claim 2, characterized in that, The energy storage connection port supports connection to at least one energy storage battery pack with a rated power of 261kW.

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