DC charging station for charging an electric vehicle

Abstract

DC charging station (100; 200; 300) for charging an electric vehicle comprising: - two DC charging station input terminals (102, 104) for an input DC voltage (VE) with a first voltage range provided by a central unit; - a first DC voltage converter (106; 302) for converting the input DC voltage (VE) into an output DC voltage (VA) with a second voltage range; - two DC charging station output terminals (108, 110) for providing the output DC voltage (VA) to the electric vehicle; characterized in that the DC charging station (100; 200; 300) comprises a control unit (112) with a first communication interface (114) for communication between the DC charging station (100; 200; 300) and the central unit, and that the DC charging station (100; 200;300) comprises a power measurement unit (224) which is connected to the DC charging station input terminals (102, 104) and which determines the power delivered to the electric vehicle.;

Description

TECHNICAL AREA The present invention relates to a DC charging station for charging an electric vehicle. STATE OF THE ART Charging devices are generally used to charge electric vehicles. At home, these are called wallboxes, as they are usually mounted on a house wall. In public spaces, charging stations are often installed. Wallboxes and charging stations usually have one or more sockets. These sockets are also referred to as charging points. A charging cable with a plug can be connected to the socket or is already attached, thus electrically connecting the electric vehicle to the charging device. Several types of connectors are known, such as: - Schuko plug; - IEC 62196-2 Type 1, a single-phase AC connection; - IEC 62196-2 Type 2, a single- and three-phase AC connection; and - IEC 62196-2 Type 3, a single- and three-phase AC connection with protective mechanisms. Type 2 connectors are predominantly used in Europe and also allow charging with direct current at power outputs up to 120kW (Type 2 Tesla - DC charging via Type 2 connector). When charging with alternating current (AC), electric vehicles typically have a converter that transforms the AC into the direct current (DC) required for battery charging. However, for fast, high-power charging, a large and expensive converter would be necessary in every electric vehicle. Therefore, the industry is increasingly relying on direct current (DC) charging stations, also known as DC charging stations or DC fast chargers, for fast charging. The following fast-charging connectors have become established so far: - CCS, Combined Charging System, is a standard developed by German car manufacturers and mandatory throughout the EU since 2014. It describes charging with both alternating current (AC) and direct current (DC). The electric vehicle connector is equipped with a Type 2 connector for AC charging and two additional high-power DC charging pins for DC charging. - CHAdeMO is a standard developed by, among others, Japanese car manufacturers. - Tesla Supercharger is a proprietary technology from Tesla for charging Tesla electric vehicles. German patent application DE102015110023 also discloses a charging station or central unit for charging a plug-in vehicle at a charging point, wherein this charging station comprises a power transformer, several rectifier modules and a regenerative buffer storage unit. TASK OF INVENTION Therefore, the object of the present invention is to improve the interaction of a DC charging station with a central unit. REVELATION OF THE INVENTION According to the invention, a DC charging station is provided for charging an electric vehicle according to claim 1. The DC charging station according to the invention preferably comprises two DC charging station input terminals for an input DC voltage with a first voltage range, wherein the input DC voltage is provided by a central unit. Furthermore, the DC charging station according to the invention comprises a first DC-DC converter for converting the input DC voltage into an output DC voltage with a second voltage range, as well as two DC charging station output terminals for providing the output DC voltage to the electric vehicle. The DC charging station according to the invention can further comprise a control unit with a first communication interface for communication between the DC charging station and the central unit. DC charging stations are also known as DC charging stations, DC columns, DC charging stations or DC fast chargers. The term electric vehicle should preferably encompass the following meanings: - Pure electric vehicles, powered solely by battery power, also called battery electric vehicles; - Vehicles with electric drive and range extender; - Hybrid vehicles; - Plug-in hybrids; and - Fuel cell vehicles. Charging, in this context, preferably refers to supplying electrical energy to a rechargeable battery. Rechargeable batteries can also be called accumulators or batteries. Their use in an electric vehicle is preferably described as a drive or traction battery. It is generally desirable to be able to charge batteries quickly. Fast charging is particularly advantageous on long journeys that exceed the range of an electric vehicle battery. A battery can either be charged over a long period with low power or with high power in a short time; the charging energy equals power times charging time. A DC-DC converter, also known as a DC-DC converter, is generally an electrical circuit that converts a DC voltage supplied at its input into a DC voltage with a higher, lower, or inverted voltage level. DC-DC converters typically have two input and two output terminals. In a preferred embodiment, the control unit transmits or receives at least one of the following pieces of information via the first communication interface: - status of the DC charging station and / or - data on the maximum power delivered by the DC charging station and / or - charging energy value and / or - charging time value and / or - electric vehicle identification information and / or - software update data. The status of the DC power column includes, for example: - information on whether an electric vehicle is connected for charging or not and / or - information on whether an electric vehicle is currently being charged and / or - information on the connection of one or more of the DC power converters. - the available energy, power, voltage, operating state and future operating states of the central unit (e.g. energy availability forecasts based on energy supply connections (photovoltaic power, biomass power production)). The charging energy value preferably comprises the product of charging time and charging power. The charging energy value and / or the charging time value can serve as a basis for calculating the sales price for battery charging and / or as customer information. Based on the electric vehicle identification information, the central unit or the DC charging station can determine the maximum charging power permissible for the connected electric vehicle and deliver a corresponding maximum power, making it available to the DC charging station. A central unit can include and control one or more DC charging stations. The DC charging station according to the invention can also improve energy efficiency. According to another preferred embodiment, the control unit can support a serial communication standard, in particular Ethernet, at the first communication interface. Wired communication, such as Ethernet, can be advantageous compared to wireless communication between the central unit and the DC charging station, for example, to reduce the influence of high-frequency interference generated in the DC charging station or the environment. Ethernet cables, routers, and network cards are generally inexpensive and allow high data rates; PCs and industrial computers are often already equipped with an Ethernet interface as standard and can be used for the control unit or the central unit. Advantageous link lengths of up to approximately 100 m are possible with Ethernet copper cables, and typically much greater lengths with Ethernet fiber optic cables. In a further advantageous embodiment of the invention, the control unit comprises a second communication interface for communication between the DC charging station and the electric vehicle. The second communication interface allows the control unit and a battery management system of the electric vehicle to communicate with each other using a communication protocol. The battery management system can, for example: - transmit the current state of charge of the electric vehicle battery and / or - the DC voltage and maximum charging current or maximum charging power and / or - the instantaneous voltage of the battery and / or - the battery temperature to the control unit. The first communication interface allows the control unit to receive software update data in order to update a communication protocol for the second communication interface. This enables the DC charging station to communicate with, for example, the latest electric vehicles even while charging. According to further training, the control unit can support at least two different communication protocols at the second communication interface, e.g., CHAdeMO and / or CCS and / or Tesla Supercharger. This allows electric vehicles with different connectors to be charged at a single charging point at such a DC charging station. Another preferred embodiment may consist in the DC charging station being equipped with a second DC-DC converter, which is optionally connected in parallel or in series with the first DC-DC converter. Connecting DC-DC converters in series results in the addition of their output DC voltages. Connecting them in parallel increases the output DC current. Increasing the output DC current at the same output DC voltage increases the output power of the DC-DC converters. This allows the DC-DC charging station to provide different charging voltages and charging powers. For example, when charging a lithium-ion battery, the charging power is initially increased to maximum and then gradually reduced. The DC-DC charging station can have multiple charging points. Depending on the charging process, the control unit can switch the DC-DC converters from one charging point to another. The DC-DC charging station can include a third, fourth, and possibly more DC-DC converters. The series or parallel connection...Connecting all DC-DC converters in parallel essentially achieves the aforementioned effects. The DC charging station according to the invention can therefore be designed modularly and thus easily expandable. This is advantageous, for example, for installation in existing public and private infrastructure. According to a further preferred embodiment, the DC charging station comprises a switching matrix that is connected to the control unit, to at least one input terminal of each or at least several DC-DC converters, and to the DC charging station's input terminals. The control unit can control the switching matrix such that all DC-DC converters are connected either in parallel or in series. Preferably, the DC charging station comprises an insulation measuring unit connected to the DC charging station's input terminals and to earth or ground. The insulation measuring unit measures the insulation of the DC charging station from earth and, depending on the measurement, electrically disconnects the DC charging station from the electric vehicle. The insulation measuring unit can be used to assess the functionality and safety of the DC charging station and can also detect defects at an early stage. The central unit can comprise a central DC voltage source, a transformer, and / or a buffer storage system, or a direct feed from photovoltaic generation, which generates the input DC voltage and provides one or more DC charging stations. The insulation measurement unit can advantageously be arranged in each individual DC charging station and determine only the local insulation within that specific charging station, disconnecting it from the electric vehicle if necessary. Furthermore, the DC charging station according to one of the preceding claims can be equipped with a power measuring unit connected to the DC charging station's input terminals, which determines the power delivered to the electric vehicle and / or the charging time. The charging energy value preferably comprises the product of charging time, or charging time value, and charging power. The charging energy value and / or the charging time value can serve as the basis for calculating a sales price for battery charging and / or as customer information. Furthermore, the DC charging station can include a temperature measuring unit designed to control the power output of the DC charging station depending on the measured temperature. DC charging stations should preferably be able to deliver full power within an ambient temperature range of -20°C to 45°C. According to Joule's first law, current-carrying components of the DC charging station generally generate a certain amount of heat energy. If the temperature measuring unit detects an ambient temperature or DC charging station temperature above a predetermined limit, the temperature measuring unit, via the control unit, can reduce the power output of the DC charging station and thus of the current-carrying components to prevent overheating, melting, or fire. According to a further development, the DC charging station includes a main switch connected in series between the first DC-DC converter and one of the DC charging station's input terminals. The main switch is designed to selectively connect or disconnect the first DC-DC converter from one of the DC charging station's input terminals. The at least one main switch can be controlled based on an emergency stop signal, a system fault signal, or the DC charging station's insulation from ground. The DC charging station can include an emergency stop switch operated by a DC charging station user, which generates an emergency stop signal. The control unit and / or the central unit can generate the system fault signal in the event of a malfunction. The insulation measurement unit can control the main switch based on the measured insulation resistance.Furthermore, a main switch can be provided for each DC charging station input connection. The term "connected" preferably includes the meanings "electrically connected", "electrically conductively connected" and "coupled". BRIEF DESCRIPTION OF THE DRAWINGS Exemplary embodiments of the invention are explained with reference to the drawings and the following description. Figure 1 shows a DC charging station according to the invention, Figure 2 another DC charging station according to the invention, and Figure 3 another DC charging station according to the invention. FORM OF EXECUTION OF THE INVENTION Fig. 1 shows a DC charging station 100 for charging an electric vehicle battery. The DC charging station 100 comprises two DC charging station input terminals 102, 104 for an input DC voltage VE with a first voltage range of 0 V to 200 V or from 0 V to 920 V, with ground potential 0 V at the DC charging station input terminal 104. The input DC voltage is provided by a central unit and can be configured as either +1000 V to ground or ±500 V to ground within the framework of a DC bus supply. Furthermore, Fig. 1 shows a DC-DC converter 106, which forms a first DC-DC converter for converting the input DC voltage V to an output DC voltage VA with a second voltage range of 1000 V. The DC-DC converter 106 also has two DC charging station output terminals 108, 110 for supplying the output DC voltage VA to the electric vehicle, wherein a potential of 500 V is present at the DC charging station output terminal 108 and a potential of -500 V is present at the DC charging station output terminal 110. The DC charging station 106 also has a control unit 112 with an Ethernet interface 114 for communication between the DC charging station 106 and the central unit. Fig. 2 shows a DC charging station 200, comprising the components 102 to 114 of the DC charging station 100, as well as a system fault switch 202, an emergency stop switch 204, an isolation switch 206, and two main switches 208 and 210. The switches 202 to 206 are connected to the control unit 112. The main switches 208 and 210 are each connected in series between the DC charging station input terminals 102 and 104 and the DC-DC converter 106. When one of the switches 202 to 206 is actuated, it generates a signal that actuates the main switches 208 and 210 in such a way that the DC-DC converter 106 is electrically disconnected or isolated from the DC charging station input terminals 102 and 104. The DC charging station 200 includes an insulation measuring unit 212, which measures the insulation of the DC charging station 200 to earth. If the measured insulation exceeds a predetermined threshold, the insulation measuring unit 212 is activated directly, i.e.,h. without the involvement of the control unit, the isolation switch 206, which in turn generates an isolation signal that actuates the main switches 208, 210 in such a way that the DC voltage converter 106 is electrically separated or isolated from the DC voltage charging station input terminals 102, 104. The emergency stop switch 204 can be activated by a DC charging station user in an emergency. The emergency stop switch 204 generates an emergency stop signal that activates the main switches 208 and 210 in such a way that the DC-DC converter 106 is electrically disconnected or isolated from the DC charging station input terminals 102 and 104. The system fault switch 202 can be actuated by the control unit 112 and generate a system fault signal that actuates the main switches 208, 210 in such a way that the DC voltage converter 106 is electrically disconnected or isolated from the DC voltage charging station input terminals 102, 104. The control unit 112 of Fig. 2 further includes an electric vehicle communication interface 214, which forms a second communication interface for communication between the DC charging station 200 and the electric vehicle. The electric vehicle communication interface comprises three protocol interfaces for the CCS protocol 216, for the CHAdeMO protocol 218, and for the Tesla Supercharger protocol 220. The three protocol interfaces are implemented as a computer 222. The computer 222 and / or the control unit 112 comprise a mini-PC or a single-board computer, such as a Raspberry Pi, Arduino, or the like. The DC charging station 200 also includes a power measuring unit 224, which is connected to the DC charging station input terminals 102 and 104 and determines the power delivered to the electric vehicle and / or the charging time. The charging energy value comprises the product of the charging time or charging time value and the charging power. The charging energy value and / or the charging time value serve as the basis for calculating a sales price for a battery charge and / or as customer information. Fig. 3 shows a DC charging station 300, which includes the components 102 to 114 of the DC charging station 100, the components 202 to 224 of the DC charging station 200, and a second DC-DC converter 302. The second DC-DC converter 302 is optionally operated in parallel or in series with the DC-DC converter 106. The DC charging station 300 comprises two switches 304 and 306, which form a switching matrix 308. Switch 304 is connected to a first input terminal of the DC-DC converter 106 and connects the first input terminal of the DC-DC converter 106 either to a first input terminal of the DC-DC converter 302 or to the DC charging station input terminal 104. The switch 306 is connected to the first input terminal of the DC-DC converter 302 and connects the first input terminal of the DC-DC converter 302 either to the first input terminal of the DC-DC converter 106 or to the DC-DC column input terminal 102. Switches 304 and 306 are actuated by the control unit 112 in such a way that the DC voltage converters 106, 302 are connected either in parallel or in series. Connecting DC-DC converters 106 and 302 in series results in the addition of their output DC voltages. Connecting them in parallel increases their output DC current. Increasing the output DC current while maintaining the same output DC voltage VA increases the output power of the DC-DC converters 106 and 302. This allows the DC charging station to provide 300 different charging voltages and charging powers. For example, when charging a lithium-ion battery, the charging power is initially increased to maximum and then gradually reduced. All switches 202 to 210 and 304, 306 can be designed as relays, contactors or semiconductor switches, e.g. FET or bipolar transistor. QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature DE 102015110023

[0007]

Claims

DC charging station (100; 200; 300) for charging an electric vehicle comprising: - two DC charging station input terminals (102, 104) for an input DC voltage (VE) with a first voltage range provided by a central unit; - a first DC voltage converter (106; 302) for converting the input DC voltage (VE) into an output DC voltage (VA) with a second voltage range; - two DC charging station output terminals (108, 110) for providing the output DC voltage (VA) to the electric vehicle; characterized in that the DC charging station (100; 200; 300) comprises a control unit (112) with a first communication interface (114) for communication between the DC charging station (100; 200; 300) and the central unit, and that the DC charging station (100; 200;300) comprises a power measurement unit (224) which is connected to the DC charging station input terminals (102, 104) and which determines the power delivered to the electric vehicle.; DC charging station (100; 200; 300) according to claim 1, wherein the control unit (112) transmits or receives at least one of the following information via the first communication interface (114): - status of the DC charging station, - data on the maximum power delivered by the DC charging station, - charging energy value, - charging time value, - electric vehicle identification information, - software update data. DC charging station (100; 200; 300) according to claim 1 or 2, wherein the control unit at the first communication interface (114) supports a serial communication standard, in particular Ethernet. DC charging station (100; 200; 300) according to one of the preceding claims, wherein the control unit (112) comprises a second communication interface (214) for communication between the DC charging station (100; 200; 300) and the electric vehicle. DC charging station according to claim 4, wherein the control unit (112) supports at least two different communication protocols (216, 218, 220) at a charging point via the second communication interface (214). DC charging station (100; 200; 300) according to one of the preceding claims with a second DC voltage converter (302) which is optionally connected in parallel or in series with the first DC voltage converter (106). DC charging station according to claim 6 with a third and fourth DC voltage converter (106; 302), wherein all DC voltage converters (106; 302) are optionally connected in parallel or in series. DC charging station according to claim 6 or 7, comprising a switching matrix (308) which is connected to the control unit (112), to at least one input terminal of each DC voltage converter (106; 302) and to the DC charging station input terminals (102, 104), wherein the control unit (112) controls the switching matrix (308) such that all DC voltage converters (106; 302) are connected either in parallel or in series. DC charging station (100; 200; 300) according to one of the preceding claims with an insulation measuring unit (212) which is connected to the DC charging station input terminals (102, 104) and to earth, wherein the insulation measuring unit (212) measures the insulation of the DC charging station (100; 200; 300) to earth and, depending on the measurement, electrically disconnects the DC charging station (100; 200; 300) from the electric vehicle. DC charging station (100; 200; 300) according to one of the preceding claims with a temperature measuring unit designed to control the power output of the DC charging station (100; 200; 300) depending on the measured temperature. DC charging station (100; 200; 300) according to one of the preceding claims with at least one main switch (208, 210) which is connected in series between the first DC voltage converter (106; 302) and one of the DC charging station input terminals (102, 104), wherein the main switch (208, 210) is designed to selectively connect or disconnect the first DC voltage converter (106; 302) from one of the DC charging station input terminals (102, 104). DC charging station (100; 200; 300) according to claim 11, wherein the at least one main switch (208, 210) is controlled depending on an emergency stop signal, a system fault signal or the isolation of the DC charging station (100; 200; 300) from earth. System comprising a central unit and multiple DC charging stations (300) for charging electric vehicles, wherein the central unit is configured to control the DC charging stations (300) and wherein each DC charging station (300) comprises: - two DC charging station input terminals (102, 104) for an input DC voltage (VE) with a first voltage range provided by the central unit; - a first DC-DC converter (106) for converting the input DC voltage (VE) into an output DC voltage (VA) with a second voltage range; - two DC charging station output terminals (108, 110) for providing the output DC voltage (VA) to each electric vehicle;- a control unit (112) with a first communication interface (114) for communication between the DC charging stations (300) and the central unit, characterized in that the DC charging stations (300) each comprise a second DC voltage converter (302) which is optionally connected in parallel or in series with the first DC voltage converter (106). System according to claim 13, wherein the control unit (112) transmits or receives at least one of the following information via the first communication interface (114): - status of the DC charging stations, - data on the maximum power delivered by the DC charging stations, - charging energy value, - charging time value, - electric vehicle identification information, - software update data. System according to claim 13 or 14, wherein the control unit supports a serial communication standard, in particular Ethernet, at the first communication interface (114). System according to one of claims 13 to 15, wherein the control unit (112) comprises a second communication interface (214) for communication between the DC charging stations (300) and electric vehicles. System according to claim 16, wherein the control unit (112) supports at least two different communication protocols (216, 218, 220) at a charging point via the second communication interface (214). System according to claim 13 with a third and fourth DC voltage converter (106; 302), wherein all DC voltage converters (106; 302) are optionally connected in parallel or in series. System according to claim 17 or 18, comprising a switching matrix (308) connected to the control unit (112), to at least one input terminal of each DC-DC converter (106; 302) and to the DC-DC charging station input terminals (102, 104), wherein the control unit (112) controls the switching matrix (308) such that all DC-DC converters (106; 302) are connected either in parallel or in series. System according to one of claims 13 to 19 with an insulation measuring unit (212) which is connected to the DC charging station input terminals (102, 104) and to earth, wherein the insulation measuring unit (212) measures the insulation of the DC charging stations (300) to earth and, depending on the measurement, electrically disconnects the DC charging stations (300) from the electric vehicles. System according to one of claims 13 to 20 comprising a power measuring unit (224) which is connected to the DC charging station input terminals (102, 104) and which determines the power delivered to the electric vehicle and / or the charging time. System according to one of claims 13 to 21 with a temperature measuring unit designed to control the power output of the DC charging stations (300) depending on the measured temperature. System according to one of claims 13 to 22 with at least one main switch (208, 210) which is connected in series between the first DC voltage converter (106; 302) and one of the DC charging station input terminals (102, 104), wherein the main switch (208, 210) is designed to selectively connect or disconnect the first DC voltage converter (106; 302) from one of the DC charging station input terminals (102, 104). System according to claim 23, wherein the at least one main switch (208, 210) is controlled depending on an emergency stop signal, a system fault signal or the isolation of the DC charging columns (300) from earth.

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