Charging device for charging a battery, electric vehicle, charging system for charging a battery, and method for contactless charging of a battery of an electric vehicle

Abstract

A charging device (11) for charging a rechargeable battery (12), comprising a coupling unit (13) connected or connectable to a rechargeable battery (12), which coupling unit can be inductively resonantly coupled to a primary conductor (14) supplied with a charging current for charging the rechargeable battery (12), comprising a control unit (16) configured to control the charging process, and comprising a measuring device (1) for determining a relative position of a transmitter (2) emitting a periodic signal (7), comprising a receiver (3) configured to receive the signal (7) emitted by the transmitter (2), characterized in that the receiver (3) has at least two receiving units (4, 5) spaced apart from one another, and in that an evaluation unit (6) is configured to automatically determine a phase difference between the output signals generated by the receiving units (4, 5) and the signal (7) of the transmitter (2),and that the evaluation unit (6) is configured to automatically determine a distance specification describing the relative position of the transmitter (2) to the receiver (3) from the phase difference, wherein a relative position of the coupling unit (13) with respect to the primary conductor (14) can be described with the distance specification obtained by the evaluation unit (6) of the measuring device (1), and that the measuring device (1) is in control connection with the control unit (16).

Description

The invention relates to a charging device for charging an accumulator, an electric vehicle, a charging system for charging an accumulator, and a method for non-contact charging of an accumulator of an electric vehicle.Charging devices and charging systems of this type are used, for example, for the contactless recharging of batteries installed in electric vehicles. In this case, it is known to bring the electric vehicle into a spatial charging position in or at a charging station for charging the rechargeable battery and to charge the rechargeable battery in a contactless manner by resonant coupling by means of an electromagnetic field, wherein the reaching of the charging position is checked with a measuring device which can be determined by the distance between a transmitter and a receiver on the basis of an attenuation of the amplitude of an electromagnetic signal which occurs with increasing distance between these two. However, in this so-called amplitude method, it has proven disadvantageous that the relationship between amplitude height and the distance between transmitter and receiver defining the relative position is non-linear, as a result of which downstream calculations or also control methods may be made more difficult, for example.DE 102004014273 A1 describes a surface processing system having a mobile part which is self-propelled by drive means and can be navigated in a surface and having at least one fixed base part which has at least one signal transmitter, the emitted signals of which are designed to subdivide the surface into surface sections and can be recorded by at least one associated signal receiver provided on the mobile part. In order to improve the navigation of a mobile part, it is proposed that the transmitted signals are coded in accordance with the surface sections, and the coded signals received from the mobile part are input variables of an evaluation unit for determining the position of the mobile part in the surface.DE 10350746 A1 describes a system for locating the position of an object and an associated method, in which propagation time differences of a signal are determined, which signal is transmitted from an object having a transmission unit to at least three reference units having both a transmission unit and a reception unit, in order to determine the current position of the object without having to perform synchronization of clocks provided in the object and in the reference units.DE 102011010049 A1 describes that wireless charging of a battery of a vehicle is to be enabled in a simple and effective manner. For this purpose, the invention provides a vehicle having a battery, a vehicle coil for inductively absorbing a charging current for the battery, a vehicle communication device for providing information regarding the state of charge or a charging variable of the battery, wherein the information provided by the vehicle communication device can be transmitted inductively to a charging device external to the vehicle via the vehicle coil. Furthermore, according to the invention, a charging device for charging a battery of such a vehicle is provided. The invention furthermore relates to a method for charging a battery of a vehicle. Finally, the invention relates to a further method for charging a battery of a vehicle.DE 102006044937 B4 describes a device for determining the distance and / or the spatial position of a target object by means of time-of-flight measurements of ultrasonic pulses, having at least one transmitter connected to the position-variable target object for emitting ultrasonic pulses corresponding to a trigger frequency, having one or more fixed receivers for detecting the ultrasonic pulses, having an evaluation unit for carrying out time-of-flight measurements which are started corresponding to the trigger frequency, wherein the evaluation unit is operatively connected to the receiver or the receivers for stopping the time-of-flight measurements correlated in time with the detection of the ultrasonic pulses, characterized in that a synchronization station operatively connected to the evaluation unit is present for synchronizing the transmitter and the evaluation unit to a common trigger frequency, and in that a short-range synchronization path is formed at the synchronization station, which the transmitter and the evaluation unit upon a sufficient approach of the transmitter to the synchronization stationUS 2006 / 0 066 485 A1 describes a system and a method for obtaining highly accurate position information with respect to one or more mobile transmitters within a wireless tracking system, which is based on phase differences for the time difference of the arrival measurements of the transmitter(s). One or more transmitters transmit signals to multiple receivers, and the time difference of arrival of the radio signals of the transmitter(s) received at each receiver is used to determine the physical location of the transmitter(s). The high accuracy of the system is achieved by using the phase of the signals of the transmitter(s) as a reference for the time measurement. Since electromagnetic waves propagate at speed of light, a central station can determine the distance of the receiver stations from the transmitter if it knows how long a wave takes to travel from the transmitter to the receiver stations. The predetermined coordinates of the receiver stations can be used to determine the coordinate of an object embedded in or carrying the transmitter.US 2011 / 0 144 941 A1 describes methods and systems for determining multidimensional coordinates of an object based on runtime differences of multiple signals received from the object by each of a plurality of sensors. The signals may comprise optical signals in a spectrum visible to humans, which may be amplitude modulated with corresponding frequency tones. With respect to each of the sensors, an envelope may be detected and the signals within each envelope may be separated. For each of the signals, a phase difference of arrival may be determined based on a difference of the propagation times of the signal with respect to multiple sensors. The phase differences of the arrival may be converted into corresponding distance differences between a corresponding transmitter and the corresponding sensors. From the combination of the distance differences, the distance between the respective transmitters and the distance between the respective sensors, a linear distance and a perpendicular offset distance can be determined.DE 100 45 776 A1 describes that the position of a movable object is determined by a signal being emitted to the movable object in each case from a plurality of antennas of a fixed object which are arranged in a spatially distributed manner. Signal transit times are measured in the movable object, on the one hand, and the directions from which the signals are received are determined, on the other hand. From both, the exact position of the object is determined with geometric aids.WO 2008 / 071 457 A1 relates to a method and a system for position determination. It is the object of the present invention to specify a method and a system for independent and, with respect to the transmitters, contactless position determination of a receiver, wherein an exact position determination is to be ensured using inexpensive receivers and as few transmitters as possible, in particular in areas in which GPS signals are not available. The method according to the invention comprises the following method steps: emitting electromagnetic radiation of a first transmission frequency by means of the first transmitter, wherein the first transmission frequency is modulated with a first modulation frequency; emitting electromagnetic radiation of a second transmission frequency by means of the second transmitter, wherein the second transmission frequency is modulated with a second modulation frequency, and wherein the first frequency differs from the second frequency in such a way that a beat with a beat frequency is formed; measuring at least one first amplitude of the beat frequency from a first point in time at a first position of the receiver; measuring at least one second amplitude of the beat frequency from a second point in time at a second position of the receiver; and determining the second position of the receiver with respect to the first position of the receiver from the at least one first amplitude and the at least one second amplitude of the beat frequency.US 2010 / 0 271 617 A1 describes a system for measuring the position of a vehicle and a method for determining the (relative) position of a vehicle and an object. The system comprises at least two light sources capable of emitting light and arranged at a predetermined distance from each other. The system also includes at least one detector capable of measuring the emitted light. The light emitted by the light sources includes synchronized light source identification codes. The detector is configured to determine the position of the vehicle and the object on the basis of a phase difference measurement between the light emitted by the individual light sources and a comparison phase. The vehicle can consist of the at least two light sources and the detector, wherein the phase difference between the light reflected by the object and the comparison phase is measured. Alternatively, the vehicle may comprise the at least two light sources, while the object comprises the detector and the detector is arranged to obtain the comparison phase from the light received from one of the light sources. The object may be a vehicle.The invention is based on the object of making it possible to determine the relative position of a transmitter to a receiver and to avoid the disadvantages described above.According to the invention, the object is achieved in the charging device having the features specified in claim 1, in the electric vehicle having the features specified in claim 7, in the charging installation having the features specified in claim 8, and in the method for contactless charging of an accumulator having the features specified in claim 10.An important feature of the invention in a charging device for charging an accumulator having a coupling unit which is connected or can be connected to an accumulator and which can be inductively resonantly coupled to a primary conductor to which a charging current is applied for charging the accumulator, and having a control unit which is set up for controlling the charging process, is a measuring device for determining a relative position of a transmitter which emits a periodic signal with a receiver which is set up for receiving the signal emitted by the transmitter, in that the receiver has two receiving units spaced apart from one another, in that an evaluation unit is designed which is set up for automatically determining a phase difference between the output signals generated in each case by the receiving units with respect to the signal of the transmitter, and in that the evaluation unit is set up for automatically determining a distance indication describing the relative position of the transmitter with respect to the receiver from the phase difference. In order to determine the phase difference, the transmitted signal is thus recorded by the receiving units at spatially different locations. Each receiving unit receives the signal in a different phase, so that the phase difference can be determined from the phases measured at the individual receiving units. Since the measured phases are dependent on the distance travelled by the signal, a propagation time difference of the signals from the transmitter to the two receiving units can first be determined from the phase difference. If the alignment of the receiver with respect to the transmitter is known, the distance information can be determined from this. This can be carried out with the aid of the evaluation unit, with which the relative position of the transmitter to the receiver can be derived from the phase difference.The distance specification can be related, for example, to a shortest connecting line between the transmitter and the receiver, or to a projection of this shortest connecting line onto a horizontal plane, for example.In one embodiment of the invention, it can be provided, for example, that the distance specification is related to a connecting line between the receiving units. The distance information is obtained, for example, from the projection of the shortest connecting line between transmitter and receiver onto the straight line in which the connecting line between the receiving units lies. It is advantageous here that the determination of the phase difference and the determination of the relative position of the transmitter to the receiver can be facilitated. By referring the distance specification to the connecting line, a numerical value can be formed which directly takes into account the degrees of freedom of movement of the receiver or of the transmitter.In one embodiment of the invention, it can be provided that the receiver is configured to receive an electromagnetic signal of the transmitter. This has proven to be expedient for the use of the measuring device in the technical field of contactless charging of accumulators of electric vehicles.In one embodiment of the invention, it can be provided that the receiver has at least three receiving units spaced apart from one another and forming a first pair and a second pair. It is advantageous here that in such a measuring device a two-dimensional distance indication can be determined with the aid of the evaluation unit from the measured phase differences of the periodic signal of the transmitter. This distance specification can thus describe the relative position of the transmitter to the receiver even better. This is particularly favorable if the distance specification is related to a plane and is determined. In this case, a two-dimensional distance indication can be used to describe the relative position of the receiver and / or of the transmitter in this plane directly. This is particularly advantageous for use in a control unit, since the distance information can then be used directly as an input variable for position control. The pairs are preferably formed separately from one another. At least four receiving units are required for this purpose. However, it can also be provided that a receiving unit belongs to both the first pair and the second pair. Three receiving units can then also be used.If the distance specification is present as a two-dimensional numerical value with two components, the individual components can be used separately from one another for position control of the associated direction. For example, the X and Y directions of a position indication can thus be regulated and set separately in front of one another.In one embodiment of the invention, it can be provided that the receiving units are designed as antennas, in particular as coils.In one embodiment of the invention, it can be provided that the receiving units of the first pair are arranged spaced apart from one another along a first connecting line and that the receiving units of the second pair are arranged spaced apart from one another along a second connecting line. It is advantageous here that the receiver units of the receiver can be arranged at different positions and can thus each record different phases of the periodic signal. This may enable the determination of the relative position more accurately and / or more completely. It is advantageous in particular that the distance information that can be obtained in each case by the pairs can be referred to different directions.In one embodiment of the invention, it can be provided that the first connecting line and the second connecting line span a plane or that the first connecting line is oriented skew to the second connecting line. It is advantageous in this case that two-dimensional distance information can be obtained, with which the position in a predetermined plane or area can be described.It is particularly favorable if four receiving units are arranged such that the first connecting line crosses with the second connecting line and / or that the receiving units describe the corners of a preferably planar quadrilateral, wherein the first connecting line and the second connecting line lie on a diagonal of the quadrilateral.In one embodiment of the invention, it can be provided that the first pair of receiving units on the one hand and the second pair of receiving units on the other hand are formed separately from one another. It is advantageous here that the receiving units can be distributed uniformly, as a result of which the signal can be recorded with the receiving units at different points and in different phases in space, so that a more accurate determination of the relative position of the transmitter to the receiver is possible. It is also advantageous that the measurements with the two pairs cause little or no interference with one another.In one embodiment of the invention, it can be provided that the evaluation unit is configured to automatically determine a first phase difference between the output signals generated at the or a first pair of receiving units with respect to the signal of the transmitter and a second phase difference between the output signals generated at the or a second pair of receiving units with respect to the signal of the transmitter. It is advantageous here that a distance specification can be generated from each of the two phase differences. A two-dimensional distance indication can thus be provided for determining the relative position of the transmitter to the receiver.In one embodiment of the invention, it can be provided that the receiver and / or the receiving units are part of a data transmission device which serves for data communication between receiver and transmitter. It is advantageous here that, if necessary, information regarding the relative position or the distance information can be exchanged between transmitter and receiver, also for any further processing of these data. It is also advantageous that a data transmission device that may be present in any case can be used for the measurement method according to the invention.In one embodiment of the invention, it can be provided that the evaluation unit is configured to calculate a Fourier transform with respect to the output signals of the receiving units. This allows the derivation of the distance specification describing the relative position between transmitter and receiver. It is also advantageous that the phase difference can be easily determined from the transformed output signals.In one embodiment of the invention, it can be provided that the evaluation unit is configured to compare at least one output signal of the receiving units with a reference signal. The measuring method is thus less noticeable with respect to signal fluctuations. It is particularly advantageous if the phase difference is determined as the difference of the phase difference of the output signals from the reference signal.Further important features of the invention in a charging device for charging an accumulator, having a coupling unit which is connected or can be connected to an accumulator and which, for charging the accumulator, can be inductively resonantly coupled to a primary conductor to which a charging current is applied, and having a control unit which is set up for controlling the charging process, are that a relative position of the coupling unit with respect to the primary conductor can be described with the distance information obtained by the evaluation unit of the measuring device, and that the measuring device is in control connection with the control unit.In one embodiment of the invention, it can be provided that the control unit is configured to generate a control signal if the distance specification exceeds or falls below a predetermined tolerance value. It is advantageous here that the charging device can be controlled and operated with the aid of the control unit on the basis of the control signal as a function of the distance information determined. The control signal may be used in manual or automatic control to position or move the receiver to the transmitter until a desired relative position is reached.In one embodiment of the invention, it can be provided that the control unit is set up to start the charging process when a tolerance value for the distance specification is undershot and / or to end the charging process when a tolerance value for the distance specification is exceeded. It is advantageous here that the charging process of the accumulator can preferably be started automatically with the aid of the control unit. In this case, the charging device receives from the control unit a control signal which initiates the charging process as soon as the accumulator or the coupling unit has reached a desired distance from the primary conductor. The distance can be less than or equal to the tolerance value for the distance indication. As soon as the distance between the primary conductor and the coupling unit exceeds the tolerance value for the distance indication, the charging process can be interrupted by a further control signal.In one embodiment of the invention, it can be provided that the control unit is configured to generate an indication signal when a tolerance value for the distance indication is undershot and / or when a tolerance value is exceeded. It is advantageous here that a deviation from the distance between the primary conductor and the coupling unit defined by the tolerance value and necessary for charging the accumulator can be indicated. This is favorable, for example, for a manual positioning of the coupling unit with respect to the primary conductor.Important features of the invention in the electric vehicle are that an electric drive motor which can be supplied from a rechargeable battery and a charging device according to the invention, in particular as described above and / or according to one of Claims 1 to 6, are present. It is advantageous here that, in the case of such an electric vehicle, the position relative to the primary conductor can be determined and the charging process can be started manually or automatically in the manner described above as soon as the electric vehicle has reached a predefined charging position.Important features of the invention in a charging system for charging an accumulator are that a primary conductor to which a charging current can be applied, a transmitter and a charging device according to the invention, are designed, in particular as described above and / or according to one of Claims 1 to 6. It is advantageous here that the charging system can charge the rechargeable battery of the previously described electric vehicle with the aid of the primary conductor, to which the charging current can be applied, as soon as the electric vehicle with the coupling unit and the rechargeable battery has assumed the charging position with respect to the primary conductor required for charging the rechargeable battery. This loading position is preferably characterized in that the calculated or determined distance specification lies within a predetermined tolerance value. A difference between a charging device according to the invention and a charging support according to the invention can be seen in the fact that the charging system additionally comprises the primary conductor and also the combination of transmitter and receiver.In one embodiment of the invention, it can be provided that the coupling unit is arranged displaceably relative to the primary conductor, in particular on an electric vehicle. It is advantageous here that the coupling unit, which can be inductively resonantly coupled to the primary conductor to which the charging current is applied, can thus be positioned in the position required for the charging process relative to the primary conductor and as a function of the indication signal generated by the control unit. The accumulator, which is connected or connectable to the coupling unit, can thus be charged in contactless fashion. For example, the primary conductor can be used as a transmitter.In one embodiment of the invention, it can be provided that the transmitter is structurally connected to the coupling unit. It can also be provided that the transmitter is structurally connected to the primary conductor, in particular in a floor. It is advantageous here that the transmitter can be arranged selectively on the side of the electric vehicle on the coupling unit or, for example, on the primary conductor which is fixed in position with respect to the electric vehicle.In one embodiment of the invention, it can be provided that the transmitter and / or the receiver is / are designed as a data transmission unit. It is advantageous here that data, such as the distance specification or other information, can thus be transmitted and / or exchanged between the charging installation and the electric vehicle. Thus, an already existing data transmission unit or a data transmission unit necessary for another reason can be used as well. Thus, additional radio loading may be used.An important feature in a method for contactless charging of an accumulator is a measuring method for determining a relative position of a transmitter to a receiver, which method steps are provided as follows:receiving a periodic signal of the transmitter with at least two receiving units of the receiver spaced apart from one another and forming a first pair;automatically determining a first phase difference between output signals of the at least two receiving units;automatically determining a distance specification describing the relative position between the transmitter and the receiver from the determined first phase difference.Thus, a distance indication can be easily determined.In one embodiment of the invention, it can be provided that the output signals are compared with a reference signal. It is advantageous in this case that a fixed reference variable, which is given by the reference signal, can be used to determine the phase difference.In one embodiment of the invention, it can be provided that the output signals are each Fourier transformed in order to determine the phase difference between the determined signals and to determine, in particular to calculate, the relative position. For example, a fast Fourier transform (FFT) may be advantageously employed.In one embodiment of the invention, it can be provided that the distance information is read from a table in which the dependence of the distance information on the phase difference is stored. It is advantageous here that the determination of the relative position is also possible on the basis of a comparison of the determined phase differences with distance information stored in the table. This is advantageous in particular when a calculation of the distance specification is too complicated. Thus, the method can be performed with a low computational capacity requirement.In the measuring method, the following method steps can additionally be carried out:receiving the periodic signal of the transmitter with at least two receiving units of the receiver spaced apart from one another and forming a second pair, wherein at least one receiving unit of the second pair does not belong to the first pair;automatically determining a second phase difference between output signals of the second pair of receiving units;automatically determining a preferably two-dimensional distance specification describing the relative position between the transmitter and the receiver from the two determined phase differences.It is advantageous here to have two phase differences which can be evaluated separately from one another and which can be used and are used for calculating / determining a two-dimensional distance indication.Further important features of the invention in a method for the contactless charging of an accumulator of an electric vehicle from a primary conductor laid in a stationary manner are that the following method steps are provided:- automatic determination of a distance specification describing a relative position of the electric vehicle with respect to the primary conductor with a measurement method according to the invention, in particular as described above and / or according to one of claims 11 to 13, and / or using a measurement device according to the invention, in particular as described above and / or according to one of claims 1 to 5;comparing the distance information with a predetermined tolerance value, in particular stored in the evaluation unit;generating a control signal when the distance specification falls below or exceeds the tolerance value.It is advantageous here that the charging process can be started and ended automatically.In one embodiment of the invention, it can be provided that the charging of the accumulator is started by the control signal. It is advantageous here that the charging of the accumulator can be started automatically as soon as the distance specification reaches or falls below a predefined tolerance value.In one embodiment of the invention, it can be provided that the charging of the accumulator is ended by the control signal. It is advantageous here that the charging of the accumulator can be automatically interrupted as soon as the electric vehicle leaves the charging position.In one embodiment of the invention, it can be provided that the control signal is output as an indication signal. It is advantageous here that the position of the electric vehicle relative to the primary conductor can be displayed, for example, to a driver of the electric vehicle, so that the driver knows or can recognize when the electric vehicle has reached the required charging position and he can end the positioning process. Such an indication signal could be, for example, an acoustic signal, for example a tone sequence or a single signal tone, an optical signal or a display on a display or another signal of a signaling or visualization device.The invention will now be described in more detail with reference to exemplary embodiments, but is not limited to these exemplary embodiments. Further exemplary embodiments result from a combination of individual or multiple features of the claims with one another and / or with individual or multiple features of the exemplary embodiments.In a partially schematic illustration, FIG. 1 : shows a schematic diagram of a charging system according to the invention having a primary conductor and a charging device according to the invention having a coupling unit and a receiver, wherein the charging device is arranged in an electric vehicle and the primary conductor is arranged in a base plate and the electric vehicle is located above the primary conductor in the charging position, FIG. 2 shows a schematic diagram of the receiver used in FIG. 1, FIG. 3 shows an illustration of a receiver having two receiver units in an electromagnetic field, and FIG. 4 : shows a view of the receiver shown in FIG. 3 in an electromagnetic field of a primary conductor through which current flows, which serves for charging an accumulator of an electric vehicle.Figures 1 to 4 will be described together below.FIG. 1 shows a measuring device 1 for determining a relative position of a transmitter 2 emitting a periodic signal. The measuring device 1 has a receiver 3 which is configured to receive the electromagnetic signal emitted by the transmitter 2. In the exemplary embodiment, the transmitter 2 does not belong to the measuring device 1.According to FIG. 2, which shows a schematic diagram of the receiver 3, the receiver has two receiving units 4 and 5 spaced apart from one another. The receiving units 4, 5 are each designed as antennas, in particular as coils.Furthermore, an evaluation unit 6 is formed on the measuring device 1, which is configured to automatically determine a phase difference between output signals generated by the receiving units 4 and 5 in each case with respect to the electromagnetic signal of the transmitter 2.In this case, the output signals of the receiving unit 4 are present at an output 21. The output signals of the receiving unit 5 are present at an output 22.The outputs 21, 22 and the receiving units 4, 5 can be formed separately from one another, or-as shown here-it can be provided, for example, that both outputs 21, 22 have a common connection 23.The electromagnetic signal of the transmitter 2 is represented in FIGS. 3 and 4 by the field lines 7. It can be seen here that the two receiving units 4 and 5 of the receiver 3 are arranged spaced apart from one another along a connecting line 27 at a distance C. The receiving units 4, 5 thus form a first pair 24 of receiving units 4, 5.Between the transmitter 2 and the receiver 3 there is a vertical distance h which is oriented perpendicular to the distance C between the two receiving units 4 and 5. The two distances C and h result in a signal 7 transmitted by the transmitter 2 having to travel distances of different lengths until it reaches the two receiving units 4 and 5 of the receiver 3. Depending on the distance covered and a wavelength of the signal 7, the two receiving units 4 and 5 can generate output signals having different phases at the respective outputs 21, 22. These output signals thus have a phase difference with respect to one another, from which the relative position of the transmitter 2 to the receiver 3 can be determined according to known geometrical laws.In addition to the first pair 24, the measuring device 1 also has a second pair 25 with receiving units 8 and 9 as well as further receiving units belonging to the receiver 3. The receiving units 8, 9 are designed like the receiving units 4, 5, but are arranged spaced apart from one another along a second connecting line 28 (cf. FIG. 2 ). The two connecting lines 27, 28 of the two pairs of receiving units 4, 5, 8 and 9 are oriented perpendicular to the vertical distance h and are arranged crossed with respect to one another. They span a plane or are arranged skew to one another, so that with each pair 24, 25 a phase difference can be determined, which leads in each case to a distance specification, i.e. a horizontal distance I, in one direction. This distance specification is thus related to the connecting line between the respective receiving units 4, 5, 8, 9. Both distance information together result in a two-dimensional distance information.In the exemplary embodiment, the receiving units 4, 5, 8, 9 are located at the corner points of a quadrilateral. The receiving units 4, 5 of the first pair 24 are arranged at mutually opposite corners. The first pair 24 thus describes a diagonal of the quadrilateral.The receiving units 8, 9 are arranged at the remaining corners of the quadrilateral. The second pair 25 thus also describes a diagonal.The quadrilateral can lie in one plane here, or the pairs 24, 25 can be arranged one above the other.The evaluation unit 6 is configured to automatically determine a phase difference between output signals generated at the receiver 3 and the associated receiving units 4, 5, 8 and 9 with respect to the signal of the transmitter 2.With the aid of the evaluation unit 6, a distance indication describing the relative position of the transmitter 2 to the receiver 3 can be determined from the determined phase differences, which distance indication is initially two-dimensional and can be completed by the known perpendicular distance h to a spatial, three-dimensional relative position indication of the transmitter 2 to the receiver 3.For many purposes, it is sufficient to calculate the horizontal distance I from the phase difference as the distance indication. This is particularly true when the transmitter 2 and the receiver 3 are movable relative to each other only horizontally.The phase difference of the output signals of the first pair 24 can be used for calculating a first horizontal distance I.The phase difference of the output signals of the second pair 25 can be used for calculating a second horizontal distance, which can be perpendicular to the first horizontal distance, for example.The first horizontal distance I and the second horizontal distance define a two-dimensional or two-component distance specification. As a result, the relative position of the transmitter 2 to the receiver 3 can be described in a horizontal plane.The receiver 3 and / or the receiving units 4, 5, 8 and 9 can be part of a data transmission device 10 which serves for data communication between the receiver 3 and the transmitter 2. With the aid of such a data transmission device 10, for example, information regarding the relative position of the receiver 3 to the transmitter 2 or other user data can be exchanged between these two.The evaluation unit 6 can each calculate a Fourier transform with respect to the output signals of the receiving units 4, 5, 8 and 9 in order to determine the phase difference and derive the relative position.The evaluation unit 6 is configured for comparing the output signals of the receiving units 4, 5, 8 and 9 with a reference signal. From this comparison, a phase difference of the output signals with respect to the reference signal can be determined.The reference signal can be generated in the evaluation unit by a generator 26.The described measuring device 1 is part of a charging device 11 for charging an accumulator 12 with a coupling unit 13 connected or connectable to an accumulator 12, the coupling unit 13 being inductively resonantly couplable to a primary conductor 14 charged with a charging current for charging the accumulator 12. According to FIG. 1, this primary conductor 14 can be connected to a power network, not shown, via a connection 15. The primary conductor 14 can be supplied with an alternating current of constant frequency in the range of 10 kHz to 150 kHz and / or with a constant amplitude of at least 10 A, for example 60 A.The charging device 11 is also equipped with a control unit 16 that is configured to control a charging process. The charging device 11 interacts with the measuring device 1 described above, wherein a relative position of the coupling unit 13 with respect to the primary conductor 14 can be described with the distance indication I obtained by the evaluation unit 6 of the measuring device 1, in this case the horizontal distance. The measuring device 1 and the evaluation unit 6 are meanwhile in control connection with the control unit 16.The control unit 16 is used to generate control signals if the determined distance specification between the receiving units 4, 5, 8 and 9 of the receiver 3 and the primary conductor 14 exceeds or falls below a predetermined tolerance value. If the tolerance value for the distance specification is undershot, the control unit 16 passes on a control signal for starting the charging process of the accumulator 12 to the charging device 11. As soon as a distance specification is determined which exceeds the tolerance value, the control unit 16 sends a control signal to the charging device 11 which results in the termination of the charging process.With said control unit 16, it is also possible to generate an indication signal when the tolerance value for the distance indication is undershot and / or when the tolerance value is exceeded. It is thus possible to signal to a user of the charging device 11 when the coupling unit 13 is in a suitable relative position, for example within a range defined by the tolerance value, with respect to the primary conductor 14.Both the charging device 11 and the measuring device 1 are installed in an electric vehicle denoted overall by 17. The electric vehicle 17 has an electric drive 18 which can be supplied from the rechargeable battery 12.The charging device 11 and the primary conductor 14 and the transmitter 2 together form a charging system 19 for charging the rechargeable battery 12, wherein the charging system 19 comprises a movable part and a fixed-position part.In this case, the coupling unit 13 with the receiver 3 and the receiving units 4, 5, 8 and 9 is movable, i.e. movable, relative to the primary conductor 14. The primary conductor 14, on the other hand, belongs to the positionally fixed part of the charging installation 19.In the exemplary embodiment of the invention according to FIG. 1, the coupling unit 13 and the receiver 3 with the two pairs 24, 25 of receiving units 4, 5, 8 and 9 are arranged on the electric vehicle 17 in a movable and movable manner. The primary conductor 14 is stationary in a floor or a floor plate 20 and is arranged at a constant distance h, vertical in the use position, from the charging device with the receiver 3 and the coupling unit 13 of the electric vehicle 17. The distance h is dependent on the height at which the charging device 11 with the receiver 3 and the coupling unit 13 are arranged in or on the electric vehicle 17.In other exemplary embodiments, the primary conductor 14 is not arranged in a base plate 20, as shown in FIG. 1, but rather, for example, in a mat or in a floor covering.The transmitter 2 can also be structurally connected to the primary conductor 14 or identical thereto.In the present exemplary embodiment of the invention, the primary conductor 14 is also used as transmitter 2, i.e. is identical thereto.FIG. 4 shows a vertical section through a primary conductor 14. In a plane parallel to the plane of the primary conductor 14, a receiver 3 with receiving units 4, 5, 8 and 9 is also arranged in the electromagnetic field of the primary conductor 14. The primary conductor 14 is annular and serves as a transmitter 2.In an exemplary embodiment of the invention, which is not shown, it is provided that the transmitter 2 is structurally connected to the movable part of the charging installation 19, i.e. here on the electric vehicle 17, and the receiver 3 is structurally connected to the stationary primary conductor 14. In this way, the arrangement of the transmitter 2 and the receiver 3 with the receiving units 4 is reversed in relation to the exemplary embodiment of the invention shown.With the aid of the above-described elements of the invention, a measurement method described below for determining the relative position of the transmitter 2 to the receiver 3, i.e. here of the electric vehicle 17 to the primary conductor 14 installed in the floor plate 20, can be carried out.First, a periodic signal of the primary conductor 14 functioning as transmitter 2 is recorded with the two pairs 24, 25 of receiving units 4, 5, 8 and 9 of the receiver 3 spaced apart from one another. In a second step, the phase differences of the output signals of the two pairs 24, 25 of receiving units 4, 5, 8 and 9 of the receiver 3 which are spaced apart from one another are automatically determined, after which a distance specification describing the relative position between the transmitter 2 and the receiver 3 (here the relative position of the electric vehicle 17 to the primary conductor 14) arranged in the floor plate 20 is automatically determined from the phase differences determined with the aid of the evaluation unit 6. The distance specification in the present case is the horizontal distance h of the center point of the transmitter 2 from the center point of the receiver 3; the horizontal distance h results from a vertical projection of the transmitter 2 onto the plane of the receiver 3 or receiver 3 onto the plane of the transmitter 2.For this purpose, the output signals can be compared with a reference signal. To determine the distance specification describing the relative position, the output signals are each Fourier-transformed.A table is stored in the evaluation unit 6, in which the dependence of the distance information on the phase difference is stored. The respective distance information can thus be read out for the determined phase difference.All features of the invention presented thus far can be used in a method for contactless charging of the already described electric vehicle 17 with the aid of the likewise already described stationary primary conductor 14.The method is carried out according to the following method steps: In a first step, an automatic determination of a relative position of the electric vehicle 17 with respect to the primary conductor 14 is carried out using the previously described measurement method.This determined relative position is then compared with a predetermined tolerance value, in particular stored in the evaluation unit 6. On the basis of this comparison, a control signal is then generated that starts charging the accumulator 12 as soon as the distance specification reaches or falls below the predefined tolerance value. That is, as soon as the electric vehicle 17 has assumed a charging position defined by this tolerance value, characterized by a defined charging distance, the charging process begins.When this tolerance value defining the charging distance is exceeded, i.e. when the electric vehicle is moved out of its charging position, a control signal is generated, by means of which the charging process of the accumulator 13 is interrupted. Different tolerance values can also be defined for the beginning and the end in order to achieve a hysteresis behavior.Thus, the charging process, in which the primary conductor 14 is energized with full charging power, can be automatically started when the electric vehicle 17 is in the correct charging position, and automatically ended when the electric vehicle leaves the charging position again.The control signal can also be output as an indication signal for a driver of the electric vehicle 17, which indicates to the driver when the electric vehicle 17 has reached or left the charging position again.The measuring device 1 serves for determining the relative position of the transmitter 2 emitting a periodic signal to the receiver 3 which is configured to receive the signal emitted by the transmitter 2. The receiver 2 has the receiving units 4, 5, 8 and 9, which serve for the automatic determination of a phase difference between the output signals generated by the receiving units 4, 5, 8 and 9 with respect to the signal of the transmitter 2, respectively. From the phase difference, the relative position of the transmitter 2 to the receiver 3 can be determined automatically with the aid of the evaluation unit 6. The measuring device 1 can be used, for example, in checking or controlling the positioning of the electric vehicle 17 equipped with the receiver 2 with respect to the stationary primary conductor 17 charging the rechargeable battery 12 of the electric vehicle 17, which primary conductor also functions as transmitter 2.List of reference characters1 Measuring device 2 Transmitter 3 Receiver 4, 5 First pair of receiving units 6 Evaluation unit 7 Field lines of the signal 8, 9 Second pair of receiving units 10 Data transmission device 11 Charging device 12 Accumulator 13 Coupling unit 14 Primary conductor 15 Connection 16 Control unit 17 Electric vehicle 18 Drive 19 Charging installation 20 Floor or base plate 21, 22 Output 23 Connection 24 First pair of receiving units 25 Second pair of receiving units 26 Generator 27, 28 Connecting line C Distance between the receiving units 4 and 5 h Vertical distance l Horizontal distance

Claims

Charging device (11) for charging an accumulator (12), having a coupling unit (13) which is connected or can be connected to an accumulator (12) and which can be inductively resonantly coupled to a primary conductor (14) to which a charging current is applied for charging the accumulator (12), having a control unit (16) which is set up for controlling the charging process, and having a measuring device (1) for determining a relative position of a transmitter (2) which emits a periodic signal (7), having a receiver (3) which is set up for receiving the signal (7) emitted by the transmitter (2), characterized in that the receiver (3) has at least two reception units (4, 5) spaced apart from one another, in that an evaluation unit (6) is designed which is set up for automatically determining a phase difference between the output signals generated in each case by the reception units (4, 5) and the signal (7) of the transmitter (2), and that the evaluation unit (6) is configured for automatically determining a distance indication describing the relative position of the transmitter (2) to the receiver (3) from the phase difference, wherein a relative position of the coupling unit (13) with respect to the primary conductor (14) can be described with the distance indication obtained by the evaluation unit (6) of the measuring device (1), and that the measuring device (1) is in control connection with the control unit (16).Charging device (11) according to Claim 1, characterized in that the distance specification relates to a connecting line (27, 28) between the receiving units (4, 5) and / or in that the receiver (3) is configured to receive an electromagnetic signal (7) of the transmitter (2) and / or in that the receiving units (4, 5, 8, 9) are designed as antennas, in particular as coils.Charging device (11) according to either of Claims 1 and 2, characterized in that the receiver (3) has at least three reception units which are spaced apart from one another and form a first pair (24, 25) and a second pair (24, 25), and / or in that the reception units (4, 5, 8, 9) of the first pair (24, 25) are arranged spaced apart from one another along a first connecting line (27, 28) and the reception units (4, 5, 8, 9) of the second pair (24, 2, 5) are arranged spaced apart from one another along a second connecting line (27, 28), and / or in that the first connecting line (27, 28) and the second connecting line (27, 28) span a plane, or in that the first connecting line (27, 28) is oriented skewly to the second connecting line (27, 28), and / or in that the first pair (24, 25) of reception units (4, 5, 8, 9) on the one hand and the second pair of reception units (4, 5, 8, 9) on the other hand, 9) are, on the other hand, formed separately from one another and / or that the receiving units (4, 5, 8, 9) describe the corners of a quadrilateral, wherein the first connecting line (27, 28) and the second connecting line (27, 28)) lie on a diagonal of the quadrilateral.Charging device (11) according to one of Claims 1 to 3, characterized in that the evaluation unit (6) is configured to automatically determine a first phase difference between the output signals generated at the or a first pair (24, 25) of receiving units (4, 5, 8, 9) with respect to the signal (7) of the transmitter (2) and a second phase difference between the output signals generated at the or a second pair (24, 25) of receiving units (4, 5, 8, 9) with respect to the signal (7) of the transmitter (2), and / or in that the evaluation unit (6) is configured to automatically determine a preferably two-dimensional distance indication describing the relative position from the first phase difference and the second phase difference.Charging device (11) according to one of Claims 1 to 4, characterized in that the receiver (3) and / or the receiving units (4, 5, 8, 9) are part of a data transmission device (10) which serves for the data communication between receiver (3) and transmitter (2), and / or in that the evaluation unit (6) is designed to calculate a Fourier transform with respect to the output signals of the receiving units (4, 5, 8, 9), and / or in that the evaluation unit (6) is designed to compare at least one output signal of the receiving units (4, 5, 8, 9) with a reference signalCharging device (11) according to one of Claims 1 to 5, characterized in that the control unit (16) is configured to generate a control signal if the distance specification exceeds or falls below a predefined tolerance value and / or in that the control unit (16) is configured to start the charging process if a tolerance value for the distance specification falls below and / or to end the charging process if a tolerance value for the distance specification is exceeded and / or in that the control unit (16) is configured to generate an indication signal if a tolerance value for the distance specification falls below and / or if a tolerance value for the distance specification is exceeded.Electric vehicle (17) having an electric drive motor (18) which can be supplied from a rechargeable battery (12) and having a charging device (11) according to one of Claims 1 to 6.Charging system (19) for charging an accumulator (12), having a primary conductor (14) to which a charging current can be applied, a transmitter (2) and a charging device (11) according to one of Claims 1 to 6.Charging installation (19) according to Claim 8, characterized in that the coupling unit (13) is arranged such that it can be moved relative to the primary conductor (14), in particular on an electric vehicle (17), and / or in that the transmitter (2) is structurally connected to the coupling unit (13), and / or in that the transmitter (2) is structurally connected to the primary conductor (14), in particular in a floor (20), and / or in that the transmitter (2) and / or the receiver (3) is / are designed as part of a data transmission unit (10).Method for the contactless charging of an accumulator (12) of an electric vehicle (17) from a stationary primary conductor (14), characterized bythe following method steps: - automatic determination of a distance indication describing a relative position of the electric vehicle (17) with respect to the primary conductor (14), comprising: - recording a periodic signal of the transmitter with at least two receiving units (4, 5, 8, 9) of the receiver (3) spaced apart from one another and forming a first pair (24, 25); - automatic determination of a first phase difference between output signals of the at least two receiving units (4, 5, 8, 9) of the first pair; - automatic determination of a distance indication describing the relative position between the transmitter (2) and the receiver (3) from the determined first phase difference; - comparison of the distance indication with a predetermined tolerance value, in particular stored in the evaluation unit; generating a control signal when the distance specification falls below or exceeds the tolerance value.Method according to Claim 10, characterized in that the output signals are compared with a reference signal and / or in that the output signals are each Fourier-transformed and / or in that the distance information is read out from a table in which the dependence of the distance information on the phase difference is stored.Method according to either of Claims 10 and 11, characterized in that the following method steps are additionally carried out: - recording the periodic signal of the transmitter (12) with at least two reception units (4, 5, 8, 9) of the receiver (3) which are spaced apart from one another and form a second pair (24, 25), at least one reception unit (4, 5, 8, 9) of the second pair (24, 25) not belonging to the first pair (24, 25); - automatic determination of a second phase difference between output signals of the second pair of reception units (4, 5, 8, 9); - automatic determination of a preferably two-dimensional distance indication, which describes the relative position, between the transmitter (2) and the receiver (3) from the two phase differences determined.Method according to one of Claims 10 to 12, characterized in that the charging of the accumulator (12) is started by the control signal and / or in that the charging of the accumulator (12) is ended by the control signal and / or in that the control signal is output as an indication signal.

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