Method for electrically connecting an electrically powered motor vehicle and an external charging station for a DC charging process, computer program and / or computer-readable medium, control unit and motor vehicle

Abstract

A method (100) for electrically connecting an electrically powered motor vehicle (200) and an external charging station (300) for a DC charging process is provided, the method comprising: detecting (110) a resistance ratio between a first insulation resistance (215, 216, 315, 316) and a second insulation resistance (215, 216, 315, 316) during a pre-charging process; determining (120) a safety risk (260) based on the resistance ratio; and outputting (130) an exclusion signal (265) depending on the safety risk (260).

Description

[0001] The disclosure relates to a method for electrically connecting an electrically driven motor vehicle and an off-board charging station for a direct current charging process, and to a control unit configured to at least partially execute the method. Furthermore, a motor vehicle having the control unit is provided. Additionally or alternatively, a computer program is provided comprising instructions that, when executed by a computer, cause the computer to at least partially execute the method. Additionally or alternatively, a computer-readable medium is provided comprising instructions that, when executed by a computer, cause the computer to at least partially execute the method.

[0002] An energy storage device of an electrically powered motor vehicle, also known as an electric vehicle or BEV (battery electric vehicle), including plug-in hybrid electric vehicles, that draws all or part of its energy from the energy storage device or vehicle batteries. Such a motor vehicle can be charged bidirectionally at an external charging station, charging point, or charging column.

[0003] The energy storage device can be charged using direct current (DC charging), whereby the energy storage device is supplied with a direct current by the charging station to charge the energy storage device and increase its state of charge and / or to discharge it and decrease its state of charge during so-called bidirectional charging. Direct current charging is often used for charging at higher charging power levels, known as fast charging.

[0004] The vehicle and the charging station each represent a separate IT system or network. This can lead to a ground offset, for example, in the case of insulation asymmetries.

[0005] During a charging process, a plug connection ultimately establishes mechanical and electrical contact between the vehicle and the charging station. A protective conductor or equipotential bonding conductor is typically connected first as a reference potential.

[0006] Since the vehicle and the charging station are connected via three conductors, different y-voltages arise due to the insulation asymmetries. The so-called y-voltages, or common-mode voltages, are defined by a positive potential and the protective conductor, and by a negative potential and the protective conductor. Different y-voltages can occur on the charging station and vehicle sides.

[0007] Before charging begins, a differential voltage, also called x-voltage, is determined on the vehicle side between the positive and negative potentials on the vehicle side—that is, a voltage between the two high-voltage potentials. During the so-called pre-charging process, the charging station increases the differential voltage on the charging station side according to the vehicle-side differential voltage (so-called pre-charging).

[0008] The motor vehicle includes two contactors configured as switching devices for electrically connecting the motor vehicle and the charging station. It is known that the connection between the charging station and the motor vehicle is established by closing the contactors or charging contactors due to the achieved equalization of the x-voltage.

[0009] The standard "Conductive charging systems for electric vehicles - Part 23: DC charging stations for electric vehicles (IEC 61851-23:2014); German version EN 61851-23:2014; Corrigendum 2", DIN EN 61851-23 Corrigendum 2:2018-10 from 2018, together with Part 1 of IEC 61851, describes requirements for DC charging stations for supply voltages up to 1,500 V (DC). This standard specifies the connection type, which is derived from charging mode 4 described in Part 1. DC charging stations are also referred to as external or "off-board" charging stations because the power electronics for generating the required voltage are located outside the vehicle. The vehicle is supplied by the DC charging station with a DC current requested by the vehicle.

[0010] Accordingly, as a protective measure, a limitation of the accessible energy in the y-capacitors or y-capacitors, i.e. capacitors between a potential or a conductor and the protective conductor or equipotential bonding conductor, of the connected system, comprising the motor vehicle and the charging station, is provided.

[0011] Since charging stations according to older standards, for example Part 1 of the above-mentioned standard, are already in the field and do not have the protective measures specified in the above-mentioned standard, it is necessary to achieve this protection by other means.

[0012] Due to insufficiently limited touchable energy in the y-capacitors of the system consisting of the motor vehicle and the charging station, it cannot be ruled out that, in the event of high asymmetry in the insulation resistance of the charging station and / or the motor vehicle, a lethal discharge of this energy can occur via the human body upon contact, as defined in the standard "DIN IEC / TS 60479-1:2007-05 VDE V 0140-479-1:2007-05 Effects of electric current on humans and livestock - Part 1: General aspects (IEC / TS 60479-1:2005 + Corrigendum October 2006)".

[0013] Against the background of this prior art, the object of the present disclosure is to provide an improved method suitable for enriching the prior art. A specific embodiment of the disclosure can solve the problem of providing an intelligent electrical connection strategy that can achieve a lower risk to human health.

[0014] The problem is solved by the features of the independent claim. The subclaims contain optional developments of the disclosure.

[0015] According to this, the problem is solved by a method for electrically connecting an electrically powered motor vehicle and an external charging station for a direct current charging process. The method comprises: detecting a resistance ratio between a first insulation resistance and a second insulation resistance during a pre-charging process; determining a safety risk based on the resistance ratio; and outputting an exclusion signal depending on the safety risk.

[0016] It was recognized that an asymmetry of the insulation resistances can be a significant factor in the safety risk. Therefore, the asymmetry of the insulation resistances is quantified by the resistance ratio. The resistance ratio can describe a quotient between two insulation resistance values, where each of the insulation resistances can be a vehicle-side or a charging station-side insulation resistance. It was recognized that, at a given voltage and upon contact, the insulation resistances can cause a safety-relevant current to flow through the body, which can lead to a safety risk. A change in insulation resistances can occur, for example, due to aging and / or weathering, and it was recognized that it may therefore be advisable to record the insulation resistances.

[0017] The safety risk can also be characterized by a risk to human health. The insulation resistance, or more precisely the asymmetry or ratio, can cause health-critical voltages or, upon contact, currents.

[0018] It has been recognized that a critical energy level can be exceeded during the initial charging phase, i.e., a transition between pre-charging and charging, for example, by connecting capacitors on the vehicle and the charging station in parallel. Therefore, it is proposed that the resistance ratio be detected and the safety risk determined during pre-charging and, in any case, before pre-charging is completed and the vehicle-side conductors are electrically connected to the charging station-side conductors for charging the motor vehicle's energy storage device. Therefore, an exclusion signal can be issued, which, depending on the safety risk, can, for example, warn and / or prevent electrical connection.

[0019] The safety risk can be determined by considering a threshold condition. The threshold condition can, for example, relate to a current determined by the resistance ratio and a time. It has been recognized that the safety risk can be significantly determined by the factors current and time. For example, the threshold condition can relate to a physiological effect. In particular, a threshold condition can be defined according to one or more of the C1, C2, or C3 curves according to "DIN IEC / TS 60479-1:2007-05 VDE V 0140-479-1:2007-05 Effects of electric current on humans and livestock - Part 1: General aspects (IEC / TS 60479-1:2005 + Corrigendum October 2006)" from 2007.

[0020] The safety risk can be defined by multiple risk levels. This allows the exclusion signal to be issued in a differentiated manner. For example, if a safety risk defined by the C1 curve is reached, a warning can be issued to a user as a first risk level. If a safety risk defined by the C3 curve is reached, a second risk level, the electrical connection can be prevented.

[0021] The safety risk can be determined by considering the voltage of a vehicle-side y-capacitance and / or the voltage of a charging station-side y-capacitance. It was recognized that the safety risk can result from capacitances in the overall system consisting of the vehicle and the charging station. A y-capacitance describes the capacitance between a conductor and the protective conductor. Voltage-dependent energy can be stored in the capacitances, which can determine the safety risk.

[0022] The resistance ratio can be determined based on multiple voltage measurements via vehicle-mounted switching devices. The switching device can be configured to connect the vehicle-mounted conductors to the charging station-mounted conductors for charging the energy storage device. This makes it possible to avoid an absolute resistance measurement, which allows for effective measurement of the insulation resistance. The voltage measurement can relate to the voltage of a conductor upstream and downstream of the vehicle's switching device.

[0023] The exclusion signal can prevent the electrical connection of the electrically powered motor vehicle and the off-board charging station for a charging process and / or include a warning message perceptible to a user. This can provide an effective measure to mitigate a health risk.

[0024] In other words, the above description can be summarized as follows, referring to a specific embodiment that is described as non-limiting for the present disclosure: The disclosure relates to additional protective measures implemented by the vehicle in the event of a fault during charging at charging stations that do not comply with IEC 61851-23 Ed2. The basic idea is: Since the vehicle knows the voltages across its individual DC charging contactors, the vehicle can calculate whether a critical asymmetry of the insulation resistances exists in the charging station during pre-charging via the charging station. This can be calculated equivalently for the vehicle using the vehicle's internal insulation monitor. A hazard only arises from the system once the vehicle and the charging station are connected via closed contactors.Therefore, a connection (contactor closure) may only be made once it has been determined that neither of the two system components (vehicle or charging station) has insulation resistances above the critical asymmetry. In the case of a critically asymmetric component (charging station or vehicle), a critical overall asymmetry cannot be ruled out, and thus a health-endangering and / or potentially fatal contact hazard cannot be ruled out.

[0025] Furthermore, a computer program is provided, comprising instructions which, when the program is executed by a computer, cause the computer to at least partially carry out or implement the method described above.

[0026] A program code of the computer program may be in any code, in particular in a code suitable for motor vehicle controls.

[0027] What has been described above with reference to the method also applies analogously to the computer program and vice versa.

[0028] Furthermore, a control unit for a motor vehicle is provided, wherein the control unit is configured to at least partially execute or perform the method described above. Thus, the method is a computer-implemented method.

[0029] The control unit can, for example, be comprised of a battery management unit (BMU). The control unit can be an electronic control unit (ECU). The control unit can be an intelligent processor-controlled unit that can communicate with other modules, for example, via a central gateway (CGW), and that can, if necessary, form the vehicle's on-board network via fieldbuses such as the CAN bus, LIN bus, MOST bus, and FlexRay, or via automotive Ethernet, for example, together with telematics control units. It is conceivable that the control unit controls functions relevant to the driving behavior of the motor vehicle, such as engine management, power transmission, and / or regulates a charging process.

[0030] What has been described above with reference to the method and the computer program also applies analogously to the control unit and vice versa.

[0031] Furthermore, a motor vehicle comprising the control device described above is provided.

[0032] The motor vehicle may be a passenger car, in particular an automobile. The optionally automated motor vehicle may be an electrically powered motor vehicle. The motor vehicle may include an electric drive that can be powered by electrical energy provided by the energy storage device to drive the motor vehicle.

[0033] What has been described above with reference to the method, the control unit, the battery control unit and the computer program also applies analogously to the motor vehicle and vice versa.

[0034] Furthermore, a computer-readable medium, in particular a computer-readable storage medium, is provided. The computer-readable medium comprises instructions that, when the program is executed by a computer, cause the computer to at least partially execute the method described above.

[0035] This means that a computer-readable medium can be provided that contains a computer program as defined above. The computer-readable medium can be any digital data storage device, such as a USB stick, a hard drive, a CD-ROM, an SD card, or an SSD card. The computer program does not necessarily have to be stored on such a computer-readable storage medium to be provided to the motor vehicle; it can also be obtained externally via the Internet or otherwise.

[0036] What has been described above with reference to the method, the control unit, the computer program and the automated motor vehicle also applies analogously to the computer-readable medium and vice versa.

[0037] An embodiment is described below with reference to the figures. Fig. 1 schematically shows a motor vehicle according to one aspect of the disclosure; and Fig. 2 a flowchart of a method according to one aspect of the disclosure.

[0038] Fig. 1 schematically shows a motor vehicle 200 according to one aspect of the disclosure.

[0039] The motor vehicle 200 is an electrically driven motor vehicle 200. For this purpose, the motor vehicle 200 has an electric drive (not shown) and an energy storage device 205. The electric drive can be supplied with electrical energy by the energy storage device 205, which the electric drive can convert into mechanical energy. In the process, the charge level of the energy storage device 205 decreases.

[0040] The motor vehicle 200 is configured to be charged at a vehicle-external charging station 300 by means of a direct current (DC), ie, through an electrical connection between the motor vehicle 200 and the charging station 300, the energy storage device 205 can be supplied with electrical energy in order to increase the state of charge of the energy storage device 205.

[0041] To connect the motor vehicle 200 to the charging station 300, the motor vehicle 200 and the charging station 300 are configured to establish a plug connection 500 between the motor vehicle 200 and the charging station 300. For this purpose, for example, the motor vehicle 200 has a charging socket or charging receptacle, and the charging station 300 has a plug (not shown).

[0042] The charging station 300 is shown schematically and comprises three electrical conductors 321, 322, 400: a reference potential and a protective conductor 400, respectively, and, each shown with a dot-dashed line, a first charging station-side conductor 321 and a second charging station-side conductor 322.

[0043] The charging station 300 comprises a first charging station-side insulation resistor 315 arranged between the first charging station-side conductor 321 and the protective conductor 400, and a first charging station-side y-capacitance 317 arranged between the first charging station-side conductor 321 and the protective conductor 400. The charging station 300 comprises a second charging station-side insulation resistor 316 arranged between the second charging station-side conductor 322 and the protective conductor 400, and a second charging station-side y-capacitance 318 arranged between the second charging station-side conductor 322 and the protective conductor 400. Furthermore, the charging station 300 can comprise electrical resistors and / or capacitances or capacitors arranged between the first charging station-side conductor 321 and the second charging station-side conductor 322.

[0044] A charging station-side differential voltage 340 is present between the first charging station-side conductor 321 and the second charging station-side conductor 322. A first charging station-side y-voltage 311 is present between the first charging station-side conductor 321 and the protective conductor 400. A second charging station-side y-voltage 312 is present between the second charging station-side conductor 322 and the protective conductor 400. For example, the first charging station-side conductor 321 carries a positive potential (DC+ conductor) and the second charging station-side conductor 322 carries a negative potential (DC- conductor).

[0045] The motor vehicle 200 is also shown schematically and comprises three electrical conductors 221, 222, 400: the protective conductor 400, and a first vehicle-side conductor 221 and a second vehicle-side conductor 222.

[0046] The motor vehicle 200 comprises a first vehicle-side insulation resistor 215 arranged between the first vehicle-side conductor 221 and the protective conductor 400, and a first vehicle-side y-capacitance 217 arranged between the first vehicle-side conductor 221 and the protective conductor 400. The motor vehicle 200 comprises a second vehicle-side insulation resistor 216 arranged between the second vehicle-side conductor 222 and the protective conductor 400, and a second vehicle-side y-capacitance 218 arranged between the second vehicle-side conductor 222 and the protective conductor 400. Furthermore, the motor vehicle 200 can comprise electrical resistors and / or capacitances or capacitors arranged between the first vehicle-side conductor 221 and the second vehicle-side conductor 222.Furthermore, the motor vehicle 200 may comprise electrical resistors and / or capacitances or capacitors, not shown, arranged between the first vehicle-side conductor 221 and the second vehicle-side conductor 222.

[0047] A vehicle-side differential voltage 240 is present between the first vehicle-side conductor 221 and the second vehicle-side conductor 222. A first vehicle-side y-voltage 211 is present between the first vehicle-side conductor 221 and the protective conductor 400. A second vehicle-side y-voltage 212 is present between the second vehicle-side conductor 322 and the protective conductor 400. For example, the first vehicle-side conductor 221 carries a positive potential (DC+ conductor) and the second vehicle-side conductor 222 carries a negative potential (DC- conductor).

[0048] The motor vehicle 200 has a control unit 250. The control unit 250 or the motor vehicle 200 is configured to control the Fig. 2. For this purpose, the motor vehicle 200 has Fig. 1 has a first switching device 231 and a second switching device 232.

[0049] When the plug connection 500 is established, the first switching device 231 and the second switching device 232 are each open, meaning there is no electrical connection between the charging station 300 and the energy storage device 205. Precharging can take place. This means that the differential voltage 340 on the charging station side can be ramped up, i.e., increase. The protective conductor 400 can connect the motor vehicle 200 and the charging station 300 to one another in order to terminate the precharging and to complete the charging of the energy storage device 205.

[0050] The control unit 250 is configured to apply a first closing signal 251 to the first switching device 231 in order to close the first switching device 231 and thus establish an electrical connection between the first charging station-side conductor 321 and the first vehicle-side conductor 221 and thus electrically connect the charging station 300 and the energy storage device 205 via the first charging station-side conductor 321 and the first vehicle-side conductor 221.

[0051] The control unit 250 is configured to apply a second closing signal 252 to the second switching device 232 in order to close the second switching device 232 and thus establish an electrical connection between the second charging station-side conductor 322 and the second vehicle-side conductor 222 and thus electrically connect the charging station 300 and the energy storage device 205 via the second charging station-side conductor 322 and the second vehicle-side conductor 222.

[0052] If both switching devices 231, 232 are closed, a direct current charging process can be carried out to charge the energy storage device 205. The closing of the switching devices 231, 232 occurs after precharging or a precharging process ("pre-charging"), in which the charging station-side differential voltage 340, the first charging station-side y-voltage 311, and / or the second charging station-side y-voltage 312 are increased starting at a precharging time.

[0053] The control unit 250 is configured to determine a resistance ratio between a first of the insulation resistors 215, 216, 315, 316 and a second of the insulation resistors 215, 216, 315, 316 during a precharging process. For this purpose, the control unit 250 is configured to measure voltage via the switching devices 231, 232. The asymmetry of the insulation resistors 215, 216, 315, 316, i.e., the resistance ratio, can be determined from the voltage measurement.

[0054] The control unit 250 is configured to process the resistance ratio in order to determine a safety risk 260 based on the resistance ratio. Based on the resistance ratio, a relationship between the y-voltages in the connected system can be deduced. To determine the safety risk 260, the capacitances 217, 218, 317, 318 can be considered charged according to the y-voltages, whereby a characteristic energy and / or time for discharge (body current flow) results from the capacitances 217, 218, 317, 318. The safety risk 260 is thus determined taking into account a voltage of a vehicle-side y-capacitance 217, 218 and / or a voltage of a charging station-side y-capacitance 317, 318.To determine the safety risk 260, characteristic values ​​from one of the C1, C2, or C3 curves according to "DIN IEC / TS 60479-1:2007-05 VDE V 0140-479-1:2007-05 Effects of electric current on humans and livestock - Part 1: General aspects (IEC / TS 60479-1:2005 + Corrigendum October 2006)" from 2007 can be stored in the control unit 250. This allows the safety risk 260 to be determined taking into account a threshold condition relating to a current and a time, whereby the safety risk 260 is defined by several risk levels, for example the C1, C2, and C3 curves.

[0055] The control unit 250 is configured to transmit an exclusion signal 265 depending on the safety risk 260. For this purpose, the control unit 250 can transmit the exclusion signal 265 to the switching devices 231, 232 to prevent an electrical connection of the electrically driven motor vehicle 200 and the off-board charging station 300 for a charging process and / or to include a warning message 266 perceptible to a user. The warning message 266 can be transmitted via a vehicle-side user interface and / or via a user terminal connectable to the motor vehicle 200 for outputting the warning message 266.

[0056] Fig. 2 shows a flowchart of a method 100 according to one aspect of the disclosure. The method 100 is a method 100 for electrically connecting an electrically driven motor vehicle 200 and an off-board charging station 300 for a direct current charging process. Such a motor vehicle 200 and such a charging station 300 are described with reference to Fig. 1 described. Fig. 2 is made with reference to Fig. 1 described.

[0057] The procedure 100 according to Fig. 2 comprises: detecting 110 a resistance ratio between a first insulation resistance 215, 216, 315, 316 and a second insulation resistance 215, 216, 315, 316 during a pre-charging process.

[0058] The detection 110 of the resistance ratio is carried out on the basis of several voltage measurements via vehicle-side switching devices 231, 232.

[0059] A safety risk 260 is determined 120 based on the resistance ratio. The safety risk 260 is determined taking into account a threshold condition. The safety risk 260 is defined by several risk levels. The safety risk 260 is determined taking into account a voltage of a vehicle-side y-capacitance 217, 218 and / or a voltage of a charging station-side y-capacitance 317, 318.

[0060] An exclusion signal 265 is output 130 depending on the safety risk 260. The exclusion signal 265 prevents an electrical connection of the electrically driven motor vehicle 200 and the vehicle-external charging station 300 for a charging process and / or includes a warning information 266 that is perceptible to a user. List of reference symbols 100 procedures 110 Capture 120 Investigate 130 Issues 200 motor vehicles 205 Energy storage device 211 first vehicle-side y-voltage 212 second vehicle-side y-voltage 215 first vehicle-side insulation resistance 216 second vehicle-side insulation resistance 217 first vehicle-side y-capacity 218 second vehicle-side y-capacity 221 first vehicle-side conductor 222 second vehicle-side conductor 231 first switching device 232 second switching device 240 vehicle-side differential voltage 250 control unit 251 first closing signal 252 second closing signal 260 Security risk 265 Exclusion signal 266 Warning information 300 charging stations 311 first charging station-side y-voltage 312 second charging station-side y-voltage 315 first charging station insulation resistance 316 second charging station insulation resistance 317 first charging station-side y-capacity 318 second charging station-side y-capacity 321 first charging station-side conductor 322 second charging station-side conductor 340 charging station-side differential voltage 400 protective conductors 411 first voltage difference 412 second voltage difference 500 connectors QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited non-patent literature

[0000] Conductive charging systems for electric vehicles - Part 23: DC charging stations for electric vehicles (IEC 61851-23:2014

[0009] German version EN 61851-23:2014

[0009] Corrigendum 2“, DIN EN 61851-23 Corrigendum 2:2018-10 from 2018

[0009] DIN IEC / TS 60479-1:2007-05 VDE V 0140-479-1:2007-05 Effects of electric current on humans and livestock - Part 1: General aspects (IEC / TS 60479-1:2005 + Corrigendum October 2006

[0012] DIN IEC / TS 60479-1:2007-05 VDE V 0140-479-1:2007-05 Effects of electric current on humans and livestock - Part 1: General aspects (IEC / TS 60479-1:2005 + Corrigendum October 2006)" from 2007 [0019, 0054]

Claims

[1] Method (100) for electrically connecting an electrically driven motor vehicle (200) and a vehicle-external charging station (300) for a direct current charging process, the method (100) comprising: - detecting (110) a resistance ratio between a first insulation resistance (215, 216, 315, 316) and a second insulation resistance (215, 216, 315, 316) during a pre-charging process; - determining (120) a safety risk (260) based on the resistance ratio; and - issuing (130) an exclusion signal (265) depending on the security risk (260). [2] Method (100) according to claim 1, wherein the security risk (260) is determined taking into account a threshold condition. [3] The method (100) of claim 1 or 2, wherein the security risk (260) is defined by multiple risk levels. [4] Method (100) according to one of the preceding claims, wherein the safety risk (260) is determined taking into account a voltage of a vehicle-side y-capacitance (217, 218) and / or a voltage of a charging station-side y-capacitance (317, 318). [5] Method (100) according to one of the preceding claims, wherein the detection (110) of the resistance ratio is carried out on the basis of a plurality of voltage measurements via vehicle-side switching devices (231, 232). [6] Method (100) according to one of the preceding claims, wherein the exclusion signal (265) prevents an electrical connection of the electrically driven motor vehicle (200) and the vehicle-external charging station (300) for a charging process and / or comprises warning information (266) perceptible to a user. [7] Computer program and / or computer-readable medium comprising instructions which, when the program or instructions are executed by a computer, cause the computer to carry out the method (100) and / or the steps of the method (100) according to one of claims 1 to 6. [8] Control unit (250) for a motor vehicle (200), wherein the control unit (250) is configured to carry out the method (100) according to one of claims 1 to 6. [9] Motor vehicle (200) comprising the control device (250) according to claim 8.

Images