Charging cable detection

Abstract

Method for detecting a state of a connection between an electrically driven motor vehicle (1) and a corresponding charging station, wherein the motor vehicle (1) has a “Control Pilot (CP)” function with a vehicle-side “Control Pilot (CP)” line (3), characterized in that a length of a “Control Pilot” line between the motor vehicle and the charging station is measured by means of a “Power Line Communication” (PLC) chip (4), wherein the length of the “Control Pilot” line between the vehicle and the charging station using signal reflection and signal attenuation or -runtime is measured, wherein the PLC chip (4) sends a signal along the CP line between the motor vehicle and the charging station and receives the signal reflected at the end of the CP line between the motor vehicle and the charging station and running back to the PLC chip (4), wherein the length of the path traversed by the signal is determined based on the signal runtime, wherein the length of the CP line between the motor vehicle and the charging station is clearly determined from the distance traveled by the signal and a specific cable type is determined based on the length of the CP line between the motor vehicle and the charging station.

Description

The present invention relates to a method for detecting a state of a connection between an electrically driven motor vehicle and a corresponding charging station, to a corresponding device and to an electric vehicle.Now, great popularity has been experienced by so-called hybrid vehicles which are driven by at least one electric motor and a further energy converter-generally an internal combustion engine-and which draw energy from an operating fuel tank and a storage device in the vehicle for electrical energy. The internal combustion engine can be operated more frequently and longer in a favorable efficiency range in hybrid drive. Surplus energy that arises is used via a generator for the battery charge, i.e. the charging of the storage device for electrical energy.Besides hybrid vehicles, there are of course also pure electric vehicles which are driven only with electrical energy. Such electric vehicles, the batteries of which are charged by external power sources, are known as "plug-in vehicles". For such "plug-in vehicles", in addition to charging on the domestic power grid, e.g. in a parking garage, the charging possibility is provided at charging stations in public places, such as e.g. in garages or directly on the roadside in the immediate vicinity of parking places.U.S. Pat. No. 7,688,024 B2 describes a device for charge control of a vehicle. A resistor is connected to first and second terminals including a vehicle inlet. A control pilot line for the transmission of a pilot signal is connected to the first terminal. In the event that the vehicle inlet is not connected to a plug, a corresponding switch is switched off.US 5 714 876 A discloses an operating system for measuring cable length and source signal level using a simple zero IF super heterodyne receiver tuned to only two reference frequencies to generate samples of a serial digital signal at each of the two frequencies.US 2012 / 0029,728 A1 describes a charging device for a vehicle, which includes a device-side power line communication (PLC) modem, a device-side control pilot (CPLT) signal generation circuit, a device-side CPLT signal detection circuit and a device-side low-pass filter (LPF).EP 2 194 355 A1 relates to a method for determining a length of a power transmission line, the power transmission line connecting a first location to a second location, the method comprising: providing a first signal having a first carrier frequency at the first location; transmitting the first signal from the first location to the second location via the power transmission line; providing a second signal having a second frequency at the second location; measuring a first phase difference between the first signal and the second signal at the second location; calculating the length from the measured phase difference.WO 2003 / 094 765 A2 describes that fault detection and monitoring of power network quality for a power line network are performed using power line communication ("PLC") signal transmission and data processing functions.US 2012 / 0 249 066 A1 discloses a control circuit and a temperature sensor which are arranged in a cable drum. It is provided that the temperature sensor detects the temperature of a charging cable wound onto the cable drum and passes the temperature on to the control circuit. Further, a pilot control circuit generates a pilot signal having a duty ratio determined in advance according to an allowable current value of the charging cable, and transmits the signal to a vehicle via the charging cable. In addition, the control pilot circuit changes the duty ratio of the pilot signal based on the detected value of the temperature of the charging cable received from the temperature sensor.When charging the battery at a charging station, it is important that information is exchanged between the vehicle and the charging station, for example with respect to car owner or power consumption, quickly and safely. It would also be advantageous if the motor vehicle were to automatically identify the type of charging, in order to be able to provide the vehicle driver with precise information about the course of the charging process.An object of the present invention was thus to provide a method for automatically detecting a connection between an electric vehicle and a charging station, in order thus to improve user-friendliness and to speed up the charging of a corresponding storage unit for electrical energy.For this purpose, the present invention proposes a method for detecting a state of a connection between an electrically driven motor vehicle and a corresponding charging station according to patent claim 1, and a corresponding device according to patent claim 2 and an electrically driven motor vehicle according to patent claim 3.A method for detecting a state of a connection between an electrically driven motor vehicle, which has a "control pilot" function and an associated vehicle-side "control pilot" line, and a corresponding charging station is provided, in which a length of a "control pilot" line between motor vehicle and charging station is measured by means of a "power line communication" chip.A "control pilot" (CP) line is a primary control line between the electric vehicle and the charging station, which control line is connected to a device ground via a respective control circuit of the electric vehicle and performs the following functions, among other things:checking the presence and connection of the vehicle;permitting supply and shutdown of a power supply;transmitting the rated current of the charging station to the vehicle;monitoring the presence of device ground.For this purpose, a voltage- and pulse-width-modulated signal is used between charging column / charging cable of the charging station and vehicle during a charging process.Power line communication (PLC) refers to data transmission via power grids. Details of power line communication (PLC) can be found in a book by K. Dostert, "POWER LINE Communication", Francis Verlag, 2000. The following statements are made therein regarding PLC. While in the past only utility companies of PLC could make use of utility, the end of 20th century location has changed fundamentally by deregulation of telecommunications and energy markets. The capacity of typical access networks extends over a frequency range up to about 20 MHz up to data rates of 350 Mbit / s, thus providing a high potential. However, the possible uses are not unlimited, because frequency bands are required whose occupancy could impair primary radio services due to unintentional radio radiation. Defining usable ranges and level limit values therefore requires compromise. It is also important to find transmission paths which are as symmetrical as possible and on which a corresponding signal propagation takes place substantially every clock. While telecommunication networks take this aspect into account from the beginning, energy distribution networks, in particular in buildings, are usually far from the symmetrical state. A careful choice of frequency ranges and modulation methods with regard to electromagnetic compatibility and eliminating possibilities of "network conditioning" are therefore particular challenges. In Central Europe, the electrical energy supply can be divided into three levels, a high-voltage level (110 kV to 380 kV), a medium-voltage level (10 kV to 30 kV) and a low-voltage level with 0.4 kV. The different voltage levels serve for low-loss bridging of different distances. Transformers are located between the voltage levels, which are natural barriers for PLC carrier frequencies. For alternating current, the resistance of a wire increases with the frequency, more precisely with the square root of the frequency, due to the skin effect. In addition, in the case of cables, electrical losses in the insulating materials occur, which lead to a frequency-proportional increase in leakage losses. Electrical parameters of the wiring are subject to wide variances, as a result of which damping and characteristic impedance are subject to correspondingly high tolerances. A cable mostly used today has a four-sector geometry, which can be simulated with a stripline model. The values of characteristic impedance and attenuation which are important for PLC can thus be determined. When the signal is fed in between two phases, a characteristic impedance of approximately 45 to 50 Ω is obtained, with a slight frequency dependence being observed, which indicates low losses. The attenuation, on the other hand, increases with increasing frequency and reaches a value of around 50 dB at 20 MHz and a length of 1 km. Generally, therefore, the attenuation increases with frequency. In contrast to conventional communication channels, the interference on power grids cannot be modeled as additive white Gaussian noise (AWGN). This is due to the fact that, in addition to colored background noise with a relatively low spectral power density, narrowband interference from broadcast transmitters also occurs, and in particular various kinds of impulse interferers. The latter are highly time-variant, i.e. changes in the range of micro- and milliseconds must be expected. When a pulse occurs, the spectral power density rises considerably, so that bit errors or burst errors are likely during a data transmission. For a design of fast PLC systems, knowing the impulse response of the channel is required to determine important parameters such as the length of symbols. The impulse response of a channel is linked to the complex transfer function via the Fourier transform. In order to carry out necessary measurements, a return line is generally required. This has been realized especially in building installation networks where the use of a main line is not so problematic.Standard modulation techniques of telecommunications are unsuitable for power line communication (PLC). Only after suitable specific modification can the following methods be used successfully, but considerable differences in quality still result. 1. spread spectrum methods such as direct sequence spread spectrum (DSSS); 2. wideband single carrier methods; 3. wideband multicarrier methods with adaptive decision feedback equalization; 4. multicarrier methods in the form of orthogonal frequency division multiplexing (OFDM)".Only in the 3rd and 4th methods, a data stream to be transmitted need not be concentrated in a continuous spectrum, but may be distributed to subchannels with arbitrary intervening distances, if necessary. In OFDM, the number of subchannels is high and each has the same width. In particular, OFDM seems to be suitable as a modulation method. OFDM is a technique that has already proven itself in digital broadcasting and in ADSL. OFDM is robust in particular with respect to multipath propagation and various types of interference. The available spectrum B is divided into numerous narrow subchannels. The data transmission takes place simultaneously on N carriers with the frequencies f 1, f 2,... f N. Each subchannel then has the bandwidth Since the subchannels are narrow, constant attenuation and group delay time are respectively present within one channel. Equalization is simple or usually not necessary at all. This is a considerable advantage over broadband single-carrier methods.International Standard IEC 62196 relates to plug connectors (plugs), sockets, sockets and ready-made cables for electric vehicles, which are used for cable-bound charging systems. For example, such as. Wikipedia is specified for a range of• 690 V alternating voltage, at 50 to 60 Hz, at a rated current of up to 250 A;• 600 V direct voltage, at a rated current of up to 400 A.This standard provides three classes of charging modes and related cable types:Class 1: Charging modes are provided for the household power up to 16 A. A CP (control pilot) contact is not provided here in order to enable the charging process. Plugs and cables that tolerate less than 16 A are not reported by signaling, but provision is made for the maximum current intensities to be recorded on a respective device itself.Class 2: charging modes are provided for device current up to 32 A, as are commonly found in both single phase and three phase configurations. In this mode, a CP contact is used in the plug, which acts as a switch in the socket. The use of industrial plugs according to IEC 60309 is provided here, but other industrial plugs with a specification of 32 A or more can also be used. Appropriate Class 1 charging plugs without signalling can be used, but the charging current is then limited to 16 A.Class 3: Charging modes are provided for rapid charging up to 250 A. Simple plugs with CP contact according to class 2 can be used, but limit the charging current to 32 A. For higher charging currents, a suitable charging mode must be detected. The reference to the standard IEC 60309 takes over the physical parameters for a corresponding charging system up to 250 A, for example cable diameter and pin diameter in the plug. The maximum permissible charging current or the availability of digital communication is coded by means of pulse width modulation. The latter forms the basis for controlled charging of electric vehicles in order to influence a charging process in a targeted manner.It is now provided that a PLC chip uses a CP line present in an electrically driven motor vehicle, i.e. a vehicle-side CP line, to detect the state of a connection between the electrically driven motor vehicle and a corresponding charging station. For this purpose, it is provided that the length of a CP line between the motor vehicle and the charging station is measured by means of the PLC. Since the length of the CP line between the motor vehicle and the charging station depends on the charging mode, a corresponding cable type and thus the respective charging mode can be quickly determined.For this purpose, a signal is sent from the PLC chip into the CP line, which signal is reflected at the end of the CP line and returns to the PLC chip. Similar to the echo, the characteristics of the reflected signal are used to determine the signal attenuation or signal transit time, the length of the CP line and thus the charging mode.This allows the charging mode to be recognized automatically, thereby enabling a rapid charging operation.In addition, a device for detecting a state of a connection between an electrically driven motor vehicle and a corresponding charging station is provided, which device uses a method according to the invention.Furthermore, an electrically driven motor vehicle, in particular an electric vehicle, having a device according to the invention for detecting a state of a connection between the electrically driven motor vehicle and a corresponding charging station is provided.Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention. FIG. 1 schematically shows a first configuration of a cable connection in an electric vehicle, in which there is no connection between the vehicle and the charging station. FIG. 2 schematically shows a second configuration of a cable connection in an electric vehicle in which a class 1 cable is connected. FIG. 3 schematically shows a third configuration of a cable connection in an electric vehicle in which a class 2 cable is connected. FIG. 4 schematically shows a fourth configuration of a cable connection in an electric vehicle in which a class 3 cable is connected.The invention is schematically illustrated in the drawing on the basis of embodiments and is described schematically and in detail with reference to the drawing.FIG. 1 schematically shows a first configuration of a cable connection in an electric vehicle 1, in which there is no connection between the vehicle and the charging station. The cable connection of an electric vehicle 1 for charging at least one battery has, in addition to means suitable for the current flow, a PLC chip 2 for data transmission between electric vehicle 1 and a corresponding charging station. For this purpose, the PLC chip 2 uses a CP line which, when the cable is not connected, extends from the PLC chip 2 only along a vehicle-side CP line 3 as far as the socket 4 on the body of the electric vehicle 1. To determine whether a cable is connected to the vehicle 1, a signal is sent from the PLC chip 2 along the CP line, which is reflected at the end of the CP line and returns to the PLC chip 2, which checks this signal. On the basis of a signal transit time to be determined, i.e. the time between transmission and reception, a corresponding length of the CP line is determined at a known signal speed. Since no cable is connected in FIG. 1, the CP line extends only along the vehicle-side CP line 3 from the PLC chip 2 to the socket 4 and is thus relatively short. The length of the vehicle-side CP line 3 is known, so that it can be clearly established that no further cable with CP line is connected in this example. Since, furthermore, no current flow can be measured, it can also be seen that the motor vehicle is also not connected to a charging station via a class 1 cable.FIG. 2 schematically shows a second configuration of a cable connection in an electric vehicle 1, in which a class 1 cable is connected. Class 1 cables are provided for domestic electricity up to 16 A. A CP (control pilot) contact is not provided in these cables in order to enable the charging process. As a result, the CP line, analogously to FIG. 1, likewise extends only from the PLC chip 2 along the vehicle-side CP line 3 as far as the socket 4 on the vehicle 1. However, since, in contrast to FIG. 1, the electric vehicle 1 is connected to a charging station 6 via a cable 5, current flows through cable 5. The PLC chip 2 recognizes that no class 2 or 3 cable is connected by the above-described method. The simultaneous current flow draws the conclusion that a cable of class 1 is connected to the vehicle.FIG. 3 schematically shows a third configuration of a cable connection in an electric vehicle 1, in which a class 2 cable is connected. Class 2 charging modes are provided for device current up to 32 A, as are commonly found in both single phase and three phase configurations. In this mode, a CP contact is used in the plug, which functions as a switch in the socket. The use of industrial plugs according to IEC 60309 is provided here, but other industrial plugs with a specification of 32 A or more can also be used. The CP line 7 in such class 2 cables does not extend over the entire length of the respective cable, but only from the vehicle-side end of the cable to an enable module 8 with an integrated CP communication module. When the PLC chip 2 sends a signal, it is reflected at the module 8. Since the entire CP line is composed of the vehicle-side CP line 3 and the cable-side CP line 7, in contrast to FIGS. 1 and 2, the signal transit time will be longer than in the case of class 1 cables. The connection of a class 2 cable can be detected independently of the current flow, since the CP line runs separately from the current line. The presence of a current flow can be determined separately, for example the CP communication module in the enable module 8 can send a corresponding signal to the PLC chip 2.FIG. 4 schematically shows a fourth configuration of a cable connection 1 in an electric vehicle in which a class 3 cable is connected. Class 3 charging modes are provided for fast charging up to 250 A. Simple plugs with a CP module according to class 2 can be used, but limit the charging current to 32 A. For higher charging currents, a suitable charging mode must be detected. The reference to the standard IEC 60309 takes over the physical parameters for a corresponding charging system up to 250 A, for example cable diameter and pin diameter in the plug. The maximum permissible charging current or the availability of digital communication is coded by means of pulse width modulation. The latter forms the basis for controlled charging of electric vehicles in order to influence the charging process in a targeted manner. In class 3 cables, it is provided that a CP line 9 extends between the electric vehicle and the charging station; the CP module is arranged in the charging station (not shown). When the PLC chip 2 sends a signal along the CP line, this is only reflected at the level of the charging station 6, whereby the CP line is composed of the vehicle-side CP line 3 and the cable-side CP line 9, which are longer in total than the sum of the CP lines 3 and 7 from FIG. 3.Although the cable lengths are not standardized, for example, in the case of class 2 cables, a maximum distance between electric vehicle or socket 4 of the vehicle body and CP module is predefined in the enable module 8 of the class 2 cable inserted into the socket 4, which maximum distance must not be exceeded. This maximum distance is smaller than the smallest permitted class 3 cable length, so that an assignment of the cable types can be made unambiguously.On the basis of the method described, the state of a connection between an electrically driven motor vehicle and a corresponding charging station can be ascertained quickly and reliably. It is consequently detected which type of charging cable is connected to a vehicle and whether current flows through the connected cable.

Claims

Method for detecting a state of a connection between an electrically driven motor vehicle (1) and a corresponding charging station, wherein the motor vehicle (1) has a "control pilot (CP)" function with a "control pilot (CP)" line (3) on the vehicle side, characterized in that a length of a "control pilot" line between motor vehicle and charging station is measured by means of a "power line communication" (PLC) chip (4), wherein the length of the "control pilot" line between motor vehicle and charging station is measured with the aid of signal reflection and signal attenuation or signal delay, wherein the PLC chip (4) transmits a signal along the CP line between the motor vehicle and the charging station and receives the signal reflected at the end of the CP line between the motor vehicle and the charging station and running back to the PLC chip (4), wherein the length of the route traversed by the signal is determined on the basis of the signal transit time, wherein the length of the CP line between the motor vehicle and the charging station is unambiguously determined from the route traversed by the signal and a specific cable type is determined on the basis of the length of the CP line between the motor vehicle and the charging station.Device for detecting a state of a connection between an electrically driven motor vehicle and a corresponding charging station, comprising means configured to carry out a method according to claim 1.Electrically driven motor vehicle having a device according to Claim 2.

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