Electric vehicle charging system

Abstract

The invention relates to an electric vehicle charging system (10) comprising a charging connector (14) configured to receive a charging cable (18). The charging cable (18) and / or the charging connector (14) provide means (46) for guiding a coolant, cooling the charging cable (18) and / or the charging connector (14). The electric vehicle charging system (10) further comprises a thermal management unit (26) for cooling the coolant. The thermal management unit (26) comprises a vapor compression refrigeration system (30) for cooling the coolant below ambient temperature.

Description

Invention Field

[0001] This invention relates to an electric vehicle charging system for electric vehicles. Background Technology

[0002] One limiting factor for charging cables used in electric vehicles is the heat generated when large currents flow through the cables and the electrical connectors from the charging station to the vehicle's battery. This heat can be actively conducted away from the heat source using a liquid. In this way, current rates exceeding 500A are achieved. For this type of cooling arrangement, a liquid needs to be incorporated and guided from the radiator to the heat source and back. Additional devices, such as pumps, are necessary.

[0003] Prior art, US 2019 / 0315239 A1, discloses an electrical contact element for an automotive charging plug connector. The electrical contact element has a contact portion and a connecting portion, wherein the connecting portion can be connected to an electrical conductor of a cable. Coolant can be delivered to the contact element. Therefore, heat generated on the contact element is directly extracted.

[0004] US 10,109,395 B2 relates to a connection unit for a fluid-cooled cable and a system comprising a plug-in connector, a fluid-cooled cable, and the connection unit. The connection unit includes a housing having a cable connection opening, a fluid inlet opening, and a fluid outlet opening.

[0005] US 2019 / 0074628 A1 relates to a plug-in connector assembly for plug-in connection to a mating plug-in connector assembly.

[0006] Prior art DE 10 2011 100 389 A1 discloses a charging cable for transferring electrical energy to an energy storage device in an electric or hybrid vehicle. The charging cable includes a coolant guiding device disposed within a cable sheath. Summary of the Invention

[0007] One object of the present invention may be to provide an electric vehicle charging system in which a high current rate can be achieved.

[0008] This problem is solved by an electric vehicle charging system having the features of claim 1. Advantageous embodiments of the invention are described in detail in the dependent claims.

[0009] According to the present invention, an electric vehicle charging system includes a charging connector configured to receive a charging cable. The charging cable and / or charging connector provide means for guiding coolant and cooling the charging cable and / or charging connector. The electric vehicle charging system also includes a thermal management unit for cooling the coolant. The thermal management unit includes a vapor compression refrigeration system (VCRS) for cooling the coolant below ambient temperature.

[0010] The charging connector provides charging current from the charging station to the battery of the electric vehicle. Therefore, a "charging connector" is understood as a handheld device, such as a charging gun or charging port. The mating part of the charging connector on the side of the vehicle is called a socket. For charging the vehicle, the charging connector provides a charging cable. In the charging cable, at least one charging wire is arranged for conducting current to the vehicle. Therefore, the device for guiding the coolant is preferably a cooling cable or cooling conduit in which the coolant flows. However, other devices for guiding the coolant are also possible. The coolant can be any fluid, in which the cooling effect on the cable, especially the charging wire in the cable and / or connector, and correspondingly the electrical contacts of the connector, is achieved.

[0011] The term "thermal management unit" must be understood to include all components used for cooling the coolant. According to the invention, the thermal management unit includes at least a vapor compression refrigeration system. Such systems use a refrigerant that undergoes a phase change to achieve a temperature below ambient temperature. The use of a vapor compression refrigeration system allows for better cooling of connectors and / or cables compared to coolant cooled to near ambient temperature. Therefore, the vehicle can be charged with a higher current without exceeding the temperature limits of the vehicle's charging system.

[0012] Since heat loss in cables increases with decreasing wire cross-section and increasing cable length, this invention allows for reducing cable cross-section and / or using longer cables. Furthermore, by using a vapor compression refrigeration system, the vehicle charging system can also be used in areas with high ambient temperatures, such as deserts. Particularly in these areas, conventional air-cooled heat exchangers are less effective at cooling the coolant. Therefore, the usability of the vehicle charging system is improved.

[0013] In a preferred embodiment of the invention, the coolant is the same as that used in a vapor compression refrigeration system, which is used to cool the charging cable and / or charging connector. Therefore, the coolant is directly used to cool the components of the vehicle charging system. Consequently, no further circuitry is needed to cool these components, reducing the number of components. A corresponding vehicle charging system can be provided economically. Heat transfer is improved because the coolant evaporates directly in the cooling cable.

[0014] In a preferred embodiment of the invention, the vapor compression refrigeration system includes an expansion valve disposed in the charging connector for expanding the refrigerant. In other words, the refrigerant is supplied to the charging connector as a compressed fluid. By using this "teardrop" (or similar feature), the refrigerant expands directly within the charging connector, allowing the charging connector and the corresponding electrical contacts to be cooled with maximum cooling efficiency.

[0015] Alternatively, the vapor compression refrigeration system includes an expansion valve for expanding the refrigerant, which is arranged in the charging station of the electric vehicle charging system. Therefore, the charging station is a fixed component of the vehicle charging system. Typically, most components are housed in this charging station. Preferably, the vapor compression refrigeration system is also arranged in the charging station. With this arrangement, the charging connector can be made smaller compared to a configuration where the expansion valve is located in the charging connector. Maintenance of the expansion valve is improved.

[0016] Advantageously, the refrigeration loop of the vapor compression refrigeration system is configured to be separate from the coolant cooling loop, with an interconnecting heat exchanger arranged between the two loops for removing heat from the coolant. In this configuration, two independent loops are provided, which are thermally connected to each other only through the interconnecting heat exchanger. Preferably, the interconnecting heat exchanger is a counter-current heat exchanger. Because the two loops are independent of each other, the coolant and refrigerant can be freely selected without the boundary conditions of the other loop. Therefore, the coolant and refrigerant can be selected for maximum efficiency.

[0017] In a further advantageous development, the thermal management system includes a vapor compression refrigeration system for cooling the coolant supplied to the charging connector, and an air-cooled heat exchanger for cooling the coolant supplied to the charging cable. Therefore, the thermal management system comprises two completely independent cooling systems. One of these cooling systems cools the electrical contacts, while the other cools the wires in the cable. Each cooling system has an independent cooling line to provide two cooling loops.

[0018] The advantage of using two independent cooling systems is that each system can be optimized for the components to be cooled, resulting in a much lower coolant temperature at the electrical contacts than at the cables.

[0019] Since the electrical contacts are already cooled by the other cooling system, there is no need to connect a separate cooling line directly to the contacts to supply the coldest coolant. Therefore, the cable's cooling loop is preferably arranged such that coolant supply is through one pole, and coolant return is through the other pole. This simplifies the cooling loop.

[0020] Preferably, the thermal management unit includes an air precooling heat exchanger for precooling the coolant, which is arranged upstream of the interconnecting heat exchangers and between the coolant's refrigeration loop and cooling loop. Therefore, the air precooling heat exchanger exchanges heat from the coolant to the ambient air. The coolant is cooled by the air precooling heat exchanger before entering the interconnecting heat exchangers. Because the temperature of the coolant entering the interconnecting heat exchangers is already reduced, the size of the compressor stage in the refrigeration loop can be much smaller.

[0021] Since the coolant is cooled by an air pre-cooling heat exchanger, the cooling loop does not need to run continuously. Therefore, the cooling loop can be activated when needed, reducing the energy consumption of the vehicle's charging system. Furthermore, if the cooling loop fails, the charging system can still operate at least at a reduced current rate. Therefore, this arrangement is fail-safe.

[0022] In an advantageous embodiment, the same air-cooled heat exchanger is used for pre-cooling the coolant and for cooling the compressed refrigerant in the refrigeration loop. In other words, only one heat exchanger is needed to cool both the coolant and the refrigerant. Therefore, the number of components can be reduced, making this vehicle charging system more economical.

[0023] These and other features, aspects, and advantages of the invention will be better understood with reference to the accompanying drawings and the following description. In principle, identical or equivalent elements are given the same reference numerals. Attached Figure Description

[0024] The subject matter of the invention will be explained in more detail in the following description, which is illustrated in the accompanying drawings, wherein:

[0025] Figure 1 This is an electric vehicle charging system according to a first embodiment of the present invention.

[0026] Figure 2 It is an electric vehicle charging system according to a second embodiment of the present invention, and

[0027] Figure 3 This is an electric vehicle charging system according to a third embodiment of the present invention. Detailed Implementation

[0028] Figure 1An electric vehicle charging system 10 according to a first embodiment of the present invention is shown. This charging system 10 includes a charging connector 14, which must be connected to a socket (not shown) of the electric vehicle for charging the battery. The charging connector 14 is connected to a charging cable 18 extending from a charging station 22. A thermal management unit 26 is provided in the charging station 22. According to the present invention, the thermal management unit 26 includes a vapor compression refrigeration system 30 providing a cooling cycle 32. The vapor compression refrigeration system 30 includes a compressor 34 for compressing a refrigerant. An air-cooled heat exchanger 38 is arranged upstream of the compressor 34 for cooling the compressed refrigerant.

[0029] An expansion valve 42 is positioned adjacent to the air-cooled heat exchanger 38. The expansion valve 42 expands the refrigerant, causing its temperature to drop below ambient temperature. The thermal management unit 26 in the charging station 22 is connected to a coolant line 46 disposed in the charging cable 18, allowing refrigerant to be transported through the coolant line 46. In the illustrated embodiment, the coolant line 46 only cools the charging cable 18 of the vehicle charging system 10. Therefore, the coolant line 46 does not extend to the charging connector 14 for cooling the electrical contacts 50 of the charging connector 14.

[0030] exist Figure 2 The image shows an electric vehicle charging system 10 according to a second embodiment of the present invention. The second embodiment is related to... Figure 1 The difference in the first embodiment shown is that, in addition to the refrigeration loop 32 of the vapor compression refrigeration system 30, a coolant cooling loop 54 is arranged in the charging station 22. In this embodiment, the coolant loop 54 includes an air precooling heat exchanger 58 for precooling the coolant medium. An interconnecting heat exchanger 62 is arranged downstream of the air precooling heat exchanger 58. The interconnecting heat exchanger 62 is arranged between the coolant cooling loop 54 and the refrigeration loop 32. Through the interconnecting heat exchanger 62, heat from the coolant is transferred to the refrigerant in the refrigeration loop 32 to cool the coolant.

[0031] Following the interconnecting heat exchanger 62, coolant is transferred to a coolant tank 66, where it is stored. A coolant pump 70 is located downstream of the coolant tank 66. From the coolant pump 70, coolant is pumped to a coolant line 46. In this embodiment, the coolant line 46 is provided in the charging cable 18 and the charging connector 14 for cooling the electrical contacts 50 in the charging cable 18 and the charging connector 14.

[0032] In addition to the interconnecting heat exchanger 62, downstream of the interconnecting heat exchanger 62, the refrigeration loop 32 includes a compressor 34 for compressing the refrigerant. An air-cooled heat exchanger 38 is arranged after the compressor 34 for cooling the refrigerant. Upstream of the interconnecting heat exchanger 62, an expansion valve 42 is provided for expanding the refrigerant in the refrigeration loop 32.

[0033] In another embodiment not shown in the figure, the air precooling heat exchanger 58, which is disposed in the cooling loop 54 for precooling the coolant, is omitted.

[0034] Figure 3 An electric vehicle charging system 10 according to a third embodiment of the present invention is shown. This embodiment differs from the first embodiment in that, in the charging station 22, a cooling loop 54 is provided in addition to the cooling loop 32. Therefore, the cooling loop 32 cools the electrical contacts 50 of the charging connector 14, while the cooling loop 54 cools the charging cable 18. Thus, the two loops can operate independently of each other. A further difference between the third embodiment and the first embodiment is that the expansion valve 42 of the cooling loop 32 is provided in the charging connector 14. Therefore, the refrigerant first expands in the charging connector 14. This achieves a high cooling effect on the electrical contacts 50.

[0035] Reference Number List

[0036] 10 Vehicle charging system

[0037] 14 Charging connector

[0038] 18 Charging cable

[0039] 22 charging stations

[0040] 26 Thermal Management Unit

[0041] 30 Vapor compression refrigeration system

[0042] 32 Refrigeration Loop

[0043] 34 Compressor

[0044] 38. Air-cooled heat exchanger

[0045] 42 Expansion valve

[0046] 46 Coolant lines

[0047] 50 electrical contacts

[0048] 54 Cooling Loop

[0049] 58 Air precooling heat exchanger

[0050] 62 Interconnected heat exchangers

[0051] 66 Coolant Tank

[0052] 70 Coolant pump.

Claims

1. An electric vehicle charging system (10) includes a charging connector (14) configured to receive a charging cable (18), wherein the charging cable (18) and / or the charging connector (14) provide means for guiding coolant, cooling the charging cable (18) and / or the charging connector (14), and a thermal management unit (26) for cooling the coolant. Its features are, The thermal management unit (26) includes a vapor compression refrigeration system (30) for cooling the coolant below ambient temperature. The vapor compression refrigeration system (30) includes an expansion valve (42) for expanding the coolant. The expansion valve (42) is arranged in the charging connector (14), and the coolant cools the electrical contacts of the charging connector (14).

2. The electric vehicle charging system (10) according to claim 1, characterized in that, The coolant is the refrigerant of the vapor compression refrigeration system (30), which is used to cool the charging cable (18) and / or the charging connector (14).

3. The electric vehicle charging system (10) according to claim 1, characterized in that, The refrigeration loop (32) of the vapor compression refrigeration system (30) is configured to be separate from the cooling loop (54) of the coolant, wherein an interconnecting heat exchanger (62) is arranged between the two loops to remove heat from the coolant.

4. The electric vehicle charging system (10) according to any one of claims 1-3, characterized in that, The thermal management unit (26) includes a vapor compression refrigeration system (30) for cooling the coolant supplied to the charging connector (14) and an air-cooled heat exchanger (38) for cooling the coolant supplied to the charging cable (18).

5. The electric vehicle charging system (10) according to claim 3, characterized in that, The thermal management unit (26) includes an air precooling heat exchanger (58) for precooling the coolant, the air precooling heat exchanger (58) being arranged upstream of the interconnecting heat exchanger (62) and between the refrigeration loop (32) of the coolant and the cooling loop.

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