Signal adaptation device in a system for inductive power transfer

Abstract

A signal adaptation device (400) for an evaluation circuit (402) for evaluating an electromagnetic signal for operation in an inductive energy transmission system, the signal adaptation device having a signal transmission device (420), wherein the signal transmission device has an antenna connection (403) for coupling a receiving antenna (302ax), an evaluation connection (404) for coupling the evaluation circuit (402) for the electromagnetic signal, wherein the antenna connection (403) is designed to receive the electromagnetic signal, wherein the signal transmission device (420) is designed to leave the phase of the electromagnetic signal substantially unchanged, and wherein the signal transmission device (420) is designed to adapt the amplitude of the electromagnetic signal to a characteristic that can be preset by the evaluation circuit, wherein the evaluation connection is designed to supply the electromagnetic signal to the evaluation circuit (402).

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of inductive charging technology. In particular, the present invention relates to a signal adaptation device and a method for adapting an adaptable filter device. BACKGROUND

[0002] For electrically charging a pure electric vehicle (EV) or a hybrid vehicle (PHEV) which is operated with a combination of propulsion fuel and electrical energy, a system for inductive energy transfer can be used when the charging should take place in a contactless manner. In such a system, a magnetic alternating field in the frequency range of 25... 150 kHz is generated. It must be noted here that beyond this frequency band, boundary values for the emission of electromagnetic waves are determined by internationally valid standards. Since the magnetic field is used for energy transfer in principle, electromagnetic waves are inherently involved based on the fact that the magnetic field changes. However, the electromagnetic waves used in inductive charging have a wavelength of several kilometers because of the slow change of the field strength.

[0003] In order to comply with the boundary values for emissions, it is noted that the magnetic alternating field for energy transfer is operated with a fundamental oscillation which lies in the range of 25... 150 kHz. Therefore, filters can be used which remove the disturbing higher harmonics as far as possible. Furthermore, in order to comply with internationally valid standards and guidelines, it must be ensured that energy transfer only takes place with a defined quality of the coupling to one another, which is achieved by a defined orientation of the coupling elements to one another, for example by means of a positioning system as described in document EP 3 103 674 A1.

[0004] Document EP 2 868 516 A1 describes a method for adjusting the energy transferred between two resonators of a system for contactless energy transfer.

[0005] As coupling elements for energy transfer, GPMs (ground pad modules) with primary coils are used on the stationary side and CPMs (car pad modules) with secondary coils are used on the vehicle side. The GPMs and CPMs form a transformer for the coupling and energy transfer. The physical orientation of the coupling elements to one another is measured and adjusted by means of a positioning signal, for example a RKS (Remote Keyless Entry System). The transfer of the energy for the energy transfer and the positioning signal can use different transfer paths and different transfer technologies.

[0006] By using different systems in the adjacent environment and in particular by using electromagnetic waves, these systems can interfere with one another.

[0007] The task of the present application can be seen in enabling an efficient transfer of energy. SUMMARY

[0008] Correspondingly, a switching device, an oscillating circuit and a method for switching the switching device are proposed.

[0009] The subject matter of the present application is given by the features of the independent claims. Embodiments and additional aspects of the present application are given in the dependent claims and the following description.

[0010] According to one aspect, a signal adaptation device is proposed, which is used in an evaluation circuit for evaluating an electromagnetic signal for operation in an inductive energy transfer system. The signal adaptation device has an antenna connection for connecting a receiving antenna and an evaluation connection for connecting the evaluation circuit for the electromagnetic signal. The antenna connection is configured to receive the electromagnetic signal. A signal transfer device is configured to leave the phase of the electromagnetic signal substantially unchanged and to adapt the amplitude of the electromagnetic signal to a characteristic which is presettable by the evaluation circuit. Furthermore, the evaluation connection is configured to supply the electromagnetic signal to the evaluation circuit. The presettable characteristic can influence the frequency characteristic of the signal adaptation device or influence the resonance frequency of a primary resonance circuit, for example for setting the transfer coefficient.

[0011] According to a further aspect of the present application, a method for adapting an adaptable filter device of a signal adaptation device is described, which has: exciting the adaptable filter device with an excitation pulse, for example a direct current pulse; and measuring the phase of the filter with a phase measuring device of the inductive energy transfer system; and adapting the adaptable filter device by switching on and / or off at least one capacitor and / or a capacitor array relative to the filter device.

[0012] According to a still further aspect of the present application, a computer-readable storage medium is provided, on which program code is stored, which, when executed by a processor, implements a method for adapting an adaptable filter device. Such a processor can be used by a control device or a controller.

[0013] A floppy disk, a hard disk, a USB (Universal Serial Bus) storage device, a RAM (Random Access Memory), a ROM (Read Only Memory), or an EPROM (Erasable Programmable Read Only Memory) can be used as the computer-readable storage medium. An ASIC (Application-Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array) and an SSD (Solid State Drive) or a flash memory-based storage medium can also be used as the storage medium. Similarly, a network server or a cloud can be used as the storage medium. A communication network, such as the Internet, which can allow downloading of program codes, can also be regarded as a computer-readable storage medium. Radio-based network technologies and / or cable-connected network technologies can be used.

[0014] According to a further aspect of the present application, a program element is provided, which - when being executed by a processor - implements a method for adapting an adaptable filter device.

[0015] According to a further aspect of the present application, the signal adaptation device has an overvoltage protection device, wherein the overvoltage protection device is adapted to the operating frequency of the inductive energy transfer system in order to derive high voltages generated by the inductive energy transfer system.

[0016] Thereby, for example, the incident radiation can be derived into a positioning system, which operates at another frequency than the energy transfer system, and wherein the incident radiation has a harmful high voltage.

[0017] According to a further aspect of the present application, the signal transfer device further has a weakening device, wherein the weakening device is arranged for adapting the amplitude of the electromagnetic signal to a characteristic pre-settable by the evaluation circuit and forms a voltage divider with the overvoltage protection device. For example, the weakening device is switchable between a near-field characteristic and a far-field characteristic of the electromagnetic signal. In another example, the weakening device has a capacitive weakening element. For example, the capacitive weakening element forms a capacitive voltage divider and / or a capacitive weakening element together with the overvoltage protection device.

[0018] According to a further aspect of the present application, the weakening device is arranged for more strongly weakening signals above and / or below the frequency of the electromagnetic signal compared to signals at the frequency of the electromagnetic signal.

[0019] According to a further aspect of the present application, the signal transfer device further has an adaptable filter device. The adaptable filter device can be adapted such that the phase of the electromagnetic signal remains substantially unchanged and wherein the adaptable filter device is arranged for compensating for deviations of structural elements participating in the filter structure. For example, the adaptable filter device uses a phase measurement device, for example a zero-crossing measurement device, of the inductive energy transfer system for adapting the phase and / or for compensating for deviations of the structural elements.

[0020] According to another aspect of the present application, the electromagnetic signal is a positioning signal, e.g. a keyless entry system signal.

[0021] According to another aspect of the present application, the evaluation circuit is arranged for evaluating the amplitude and / or the phase of the electromagnetic signal. BRIEF DESCRIPTION OF DRAWINGS

[0022] Further exemplary embodiments of the present application are described below with reference to the accompanying drawings.

[0023] Figure 1 An inductive charging system according to an exemplary embodiment of the present application is shown.

[0024] Figure 2 A block diagram of an inductive charging system according to an exemplary embodiment of the present application is shown.

[0025] Figure 3 Side and top views onto a CPM and a GPM in different orientations relative to each other according to an exemplary embodiment of the present application are shown.

[0026] Figure 4 A schematic block diagram of a receiving structure of a positioning system according to an exemplary embodiment of the present application is shown.

[0027] Figure 5 A circuit configuration for an overvoltage protection device according to an exemplary embodiment of the present application is shown.

[0028] Figure 6 An alternative circuit configuration for an overvoltage protection device according to an exemplary embodiment of the present application is shown.

[0029] Figure 7 A series resonant tank without switching of a damping device according to an exemplary embodiment of the present application is shown.

[0030] Figure 8 A series resonant tank with switching of a damping device according to an exemplary embodiment of the present application is shown.

[0031] Figure 9 Frequency characteristics of different damping devices according to an exemplary embodiment of the present application are shown.

[0032] Figure 10 A flow chart of a method for adapting an adaptable filter device of a signal adapting device according to an exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0033] The illustrations in the drawings are for the purpose of illustrating preferred embodiments and are not intended to limit the present application. Figures 1 to 10 In the following description, like reference characters designate identical or corresponding parts throughout the several views.

[0034] In this context, the terms "capacitor" and "capacity" as well as "coil" or "choke" and "inductance" can be used in the same sense and should not be interpreted restrictively, unless otherwise noted. Furthermore, the terms "energy" and "power" can be used equivalently and should not be interpreted restrictively, unless otherwise noted.

[0035] Figure 1 An inductive charging system 100 or a system 100 for energy transfer according to an exemplary embodiment of the present application is shown. In this case a side view of a system for contactless charging of an electric vehicle is shown. Below the vehicle chassis 102 there is a vehicle pad module (CPM) 104, which is used to supply the vehicle 102 with current. For the energy transfer a magnetic field 106 is used, which inductively provides the energy of a ground pad module (GPM) 105, which is fixedly installed on the ground 103. The energy required for the charging is taken from a main connection 107, which can be not only alternating current (AC), but also direct current (DC). For the communication between the CPM 104 and the GPM 105 a separate connection means 101 is used, which can use a wireless protocol like WLAN (Wireless LAN) or NFC. This connection means can be used as a feedback channel 101 or as a communication channel 101, through which the CPM 104 and the GPM 105 can exchange information. Not only the magnetic field 106 for the energy transfer, but also the wireless signal 101 are electromagnetic waves, but they have different frequencies.

[0036] Figure 2 A block diagram of an inductive charging system 100 according to an exemplary embodiment of the present application is shown in the middle. Of interest is a system for inductive energy transfer, which can be used to contactlessly charge an electric vehicle. In such a system a magnetic alternating field 106 is generated in the frequency range of, for example, 25... 150 kHz. It must be noted here that outside this frequency band boundary values for the emission of electromagnetic waves are determined by internationally valid standards. In order to comply with the boundary values it is decisive that the magnetic alternating field 106 works with a fundamental oscillation in the range of 25... 150 kHz and contains only very small higher harmonics.

[0037] On the other hand, however, the efficiency of the power transfer should be as high as possible and therefore a square wave signal with the fundamental frequency of the magnetic alternating field is generated with the electronic switches inside the inverter 201, for example by means of MOSFETs, IGBTs, since very small losses are obtained in this way. However, the square wave signal contains considerable higher harmonics. These higher harmonics can be filtered out very well with a filter 200, for example an LC filter 200. The filter 200 can be embodied differently here. For example, Figure 2A 4th order filter 200 (Filter 4. Ordnung) is shown, but also further arrangements of capacitors and coils are possible. An input current Iin and an input voltage Uin are applied at an input 206 of the filter 200. The filter 200 has two input coils La1 and La2 in parallel and a filter input capacitor Ca and two output coils Lb1 and Lb2 in parallel and a filter output capacitor Cb. Instead of two input coils La1 and La2 in series, also a single input coil La can be used. Instead of two output coils Lb1 and Lb2 in series, also a single output coil Lb can be used.

[0038] The input coils La1 and La2 are directly connected to the output of the inverter 201. Direct in this case can mean that no further structural elements are connected in between. In this case, a series capacitor should not turn a direct connection into an indirect connection. The term "direct" can be used, among others, to express that the connection points of the respective components fall together and / or have the same electrical potential. The output coils Lb1 and Lb2 at the output 207 of the filter 200 are directly connected to the input coils La1 and La2 and to the primary resonance circuit 202. The primary resonance circuit 202 is supplied with a voltage U1 and a current I1 or IL, which is derived from the alternating current generated by the inverter 201. Based on the filtering action of the filter 200, the primary current I1 and the primary voltage U1 have a sinusoidal course.

[0039] The primary resonance circuit 202 has a primary resonance coil L1 or a primary coil L1 and a primary resonance capacitor C1 221. The primary resonance circuit 202 converts the current I1 and the voltage U1 into a magnetic alternating field 106. The magnetic alternating field 106 is coupled with a coupling factor k into the secondary resonance circuit 203 and transfers the energy from the primary circuit to the secondary circuit 203 by resonant and inductive energy transfer.

[0040] The secondary resonance circuit 203 has a secondary resonance coil L2 or a secondary coil L2 and a secondary resonance capacitor C2 222. Since the secondary resonance circuit 203 is tuned to the resonance frequency of the primary resonance circuit 202, the secondary resonance circuit 203 is excited to oscillate by the magnetic field 106 to such an extent that a secondary current I2 and a secondary voltage U2 result. They are delivered to the rectifier 204, which can provide a DC voltage at its output 220 for a load 205, for example a battery 205, an intermediate circuit 205, a traction circuit 205 or an output-side HV-DC 205 on the CPM 104 side.

[0041] The inductive charging system 100 is supplied by a DC voltage source 107 or input-side HV-DC (high voltage - direct current) or by an alternating voltage 107.

[0042] The energy transfer system 100, for example the ICS system 100, has a base station 105 or GPM 105 and a remote device 104 or CPM 104, wherein the base station 105 and the remote device 104 can be loosely coupled to each other by an inductive coupling and feedback channel 101. The loose coupling can be started from the respective positioning of the CPM 104 relative to the GPM 105.

[0043] The base station 105 or GPM 105 has a primary circuit 202 and the remote device 104 or CPM 104 has a secondary circuit 203. The primary circuit 202 has a coil LI and the secondary circuit has a coil L2. If the coils LI and L2 are in proximity to each other, a magnetic field 106 generated by the coils can pass through the respectively further coil LI, L2. The part of the magnetic field passing through the respectively further coil LI, L2 forms an inductive coupling with a coupling factor k or coupling coefficient k. This coupling forms a loosely coupled transformer 211. The part of the magnetic field 106 outside the respectively further coil LI, L2 forms a stray capacitance. The smaller this part of the stray capacitance formed, the larger the coupling factor k. However, because the movability of the GPM 105 and the CPM 104 relative to each other cannot form a transformer with a core, in the case of which the coupling factor k is essentially constant, the coupling factor in the case of the loosely coupled transformer is variable and for example related to the relative poses of the GPM 105 and the CPM 104 relative to each other.

[0044] The functional components of the GPM 105 are essentially integrated in a primary functional block 105' and the functional components of the CPM 104 are essentially integrated in a secondary functional block 104'.

[0045] Figure 3 The side and top views onto the CPM 104 and the GPM 105 are shown in different orientations relative to each other according to an exemplary embodiment of the application. The two transfer elements 104, 105 or GPM 105 and CPM 104 are shown in a position 104 min' , 14 max’ relative to each other and in a position 104 min , 14 max relative to each other at different heights Z. One of the transfer elements 105 is assigned to the primary component of the energy transfer system and is for example positioned on or in the ground 301 in the area of a charging station for a garage or the like of a vehicle for at least partially electrically operated vehicles in an inductive charging assembly. When the vehicle is in the charging position, the primary coil LI of the GPM 105 should be coaxially positioned on the vehicle to be charged (not shown) and for feeding in by the CPM 104 Figure 1 max ​wirelessly received energy and connected with its traction battery, for receiving a second transfer element 104, 104 max or a CPM 104, 104 max under a typically small secondary coil L2. Here, the energy for charging the vehicle battery is magnetically transferred from the GPM 105 to the CPM 104, 104 max The more accurately the coils L1, L2 are positioned on top of each other, the more efficient the transfer is in most cases.

[0046] In order to ensure a position of the coils L1 relative to L2 that is as coaxial as possible, the energy transfer system 100 is equipped with or connected with a positioning system 302, 302ax, 302bx, 302cx, 302ay, 302by, 302cy, 307 that uses a positioning signal (POS). The positioning system is set up in such a way that it can make it easy or even possible for itself to achieve a position in which the coils L1, L2 are well oriented relative to each other in order to achieve a good coupling of the coils L1, L2.

[0047] A prerequisite for such a positioning aid, which is independent of the relative position of the coils L1, L2 relative to each other being shown, signaled or, if necessary, evaluated for the automatic control of the vehicle into the charging position, is the determination of the position of the secondary coil L2 above the center of the primary coil L1. The charging system 100 is set up for the positioning to use an inductive method that is set up to use components of the charging system 100 that are present for forming the magnetic circuit for the energy transfer anyway. For this purpose, the secondary winding L2 is excited with a frequency of approximately 130 kHz, in particular 125 kHz, during the positioning and thus functions as a transmitting coil in the CPM 104 for the positioning system 302, 302ax, 302bx, 302cx, 302ay, 302by, 302cy, 307.

[0048] The GPM 105 with the primary coil L1 is equipped with a total of six "solenoid windings 302ax, 302bx, 302cx, 302ay, 302by, 302cy that are used as measurement coils or position signal receivers 302ax, 302bx, 302cx, 302ay, 302by, 302cy. They are applied around the ferrite component 303 of the GPM 105, in particular around the ferrite shield 303, which shields the electronic components of the primary part relative to the primary coil L1. For an accurate position determination, each three measurement coils are oriented in orthogonal directions, which are denoted as x and y directions. The three measurement coils are arranged at a defined distance x0 and y0 about the center of symmetry Z L1Symmetrical arrangement. Further numbers and further arrangement schemes of the positioning windings can also be considered.

[0049] The field generated by the secondary winding L2 by means of the positioning system 302 causes different induced voltages by the single windings 302ax, 302bx, 302cx, 302ay, 302by, 302cy depending on the position of the coil L2 relative to L1. The X / Y position of the CPM 104 relative to the GPM 105 can be determined from these voltages by the evaluation unit 307 or control device 307 of the positioning system in the GPM 105 by means of the correspondingly laid electronic devices. The GPM 105 is on the ground 301 below the vehicle and the CPM is for example fitted below the vehicle. The X / Y position of the CPM 104 relative to the GPM 105 can be determined independently of the height Z, that is to say independently of the vertical spacing of the coils L1, L2 perpendicular to their plane. The directions X and Y and the height Z are denoted as arrows in Figure 1 The direction of travel of the vehicle can extend in the X direction, as is shown by the arrow 308.

[0050] The system 105 of the charging station or of the further primary component communicates with the system 104 of the vehicle usually via wireless connection means 101, for example via radio, WLAN or Bluetooth. The information learned in the evaluation unit 307 can thus also be transmitted to the vehicle via the relative position of the energy transfer coils L1, L2 relative to one another and there via an interface, for example a field bus, in particular a CAN bus (controller area network), to a display or similar display unit and made accessible to the driver.

[0051] The measurement magnetic field (not shown in Figure 1 The measurement magnetic field can alternatively be generated by independent transmitting antennas, for example by the secondary coil L2 of the CPM 104 arranged on the vehicle. These independent antennas can also be provided as a supplement to the CPM 104 which generates the measurement magnetic field itself and be integrated into this CPM 104. These transmitting antennas can for example be constructed in the form of rod antennas or also as solenoid antennas and if necessary also be arranged outside the CPM 104 as external transmitting antennas on the vehicle. In certain cases it can also be considered to use a coil around the CPM 104 ferrite element as a transmitting antenna.

[0052] When the position is determined by means of the positioning system, the voltage occurring on the windings 302ax, 302bx, 302cx, 302ay, 302by and 302cy is ascertained as a function of the position by means of at least one voltage measuring assembly connected to the measuring coils 302ax, 302bx, 302cx, 302ay, 302by, 302cy, which can be integrated into the evaluation unit 307 or can be front-coupled to the evaluation unit, in particular as a function of the lateral offset between the symmetry centers Z of the coils L1, L2 of the CPM 104 and the GPM 105 L1 and Z L2 or Z' L2 The measuring field is generated by the coil L2. At large distances of the CPM 104 and the GPM 105 relative to one another, the effect of the coil L2 can be strengthened by means of an external antenna. At small distances, the position determination can be performed by means of the measuring field, which is generated by the coil L2 alone, without the use of an external antenna.

[0053] For the inductive and / or contactless transfer of electrical energy from the GPM 105 to the CPM 104 onto the vehicle, each unit thus comprises a main coil L1, L2. The main coil on the side that supplies energy is also referred to as the primary coil L1, and the main coil on the side that receives energy is referred to as the secondary coil L2. The two main coils are coupled by means of a resonant magnetic field 106, which is generated by the coil electronics. By means of this magnetic field, energy is generally transferred from the GPM 105 to the CPM 104.

[0054] In addition to the system 302, 307 POS for positioning, the energy transfer system 100 can also have further systems and / or sensors. For example, sensors of a FOD system for identifying electrically conductive or magnetically acting foreign objects or sensors of a LOD system for detecting organic objects can be present in addition to the measuring coils 302ax, 302bx, 302cx, 302ay, 302by, 302cy. All these systems can use electromagnetic waves and / or fields in order to perform their function.

[0055] Since even the resonant magnetic field for the energy transfer essentially involves electromagnetic waves and / or electromagnetic fields, an interaction of the structural elements can occur, since the generators for the electromagnetic waves can represent, of their own accord in a passive state, an interference for further electromagnetic systems in such a way that these generators are excited to oscillate by electromagnetic waves acting on them from the outside and become, of their own accord, transmitters, which, however, mostly act as interference transmitters for the actual signal.

[0056] The main coil Ll or energy transfer coil Ll needs to be highly inductive. By additional electronic structural elements, for example an inverter with diode lines and capacitors, highly inductive oscillation loops can be generated, which influence the signals of the system LOD, FOD and POS, 302, 307 and can thus lead to a limited quality and performance of the system LOD, FOD and POS, 302, 307. In the case of the positioning system 302, 307 POS, a second transmitter can be generated, since the primary resonance loop 202 can be excited to oscillate. Furthermore, a magnetic coupling can occur between the main coil Ll and the measuring or receiving coils 302ax, 302bx, 302cx, 302ay, 302by, 302cy of the positioning system 302, 307. By means of this magnetic coupling via the law of electromagnetic induction, the signals of the sensors can be transferred in space to further physical locations by means of an inductively measured current or by means of an induced current. The sensors at these further physical locations then no longer measure only the use signal of the signal transmitter, but additionally also measure the superposition of this use signal with signals which are caused by the sensors at the further locations.

[0057] Thus, although these frequencies are different from one another and no interference of the systems with one another should occur. However, tolerances in the construction can cause the occurrence of reactions of the individual loops, although these signals are in further frequency ranges and are not at all determined for these frequency ranges. This can lead to a destruction of the construction, since the systems work with very different voltages. However, during the operation of the POS, LOD, FOD with voltages in the μV range, the energy transfer system works with significantly higher voltages, for example 6000 V, and can destroy the electronic devices of the further systems.

[0058] Figure 4 A schematic block connection diagram of a receiving structure 401 of the positioning system 302, 307 according to an exemplary embodiment of the application is shown. The POS receiving structure 401 essentially has three functional blocks 302ax, 400, 402.

[0059] The positioning system 302, 307 can essentially be provided with six receiving antennas 302ax, 302bx, 302cx, 302ay, 302by, 302cy. Of these receiving antennas, only the antenna 302ax will be considered in the following, since the structure of the further antennas 302bx, 302cx, 302ay, 302by, 302cy is essentially the same.

[0060] Via the receiving antenna 302ax, electromagnetic signals, for example positioning signals POS, are received. Although the present description essentially only discusses the POS signals, the present description applies to any possible electromagnetic receiving device which is operated in the vicinity of a strong magnetic field 106.

[0061] The receiving antenna 302ax is connected to the antenna connection 403 of the signal adaptation device 400. The signal received by the receiving antenna 302ax is to be further transmitted to the control device 307 with the signal evaluation circuit 402 or to the evaluation circuit 402 for evaluating the electromagnetic signal for the operation in the inductive energy transfer system. The evaluation circuit 402 is coupled at the evaluation connection 404 of the signal adaptation device 400. The evaluation circuit 402 has an amplitude evaluation device 405 for evaluating the amplitude of the received signal and / or for locating data in the signal and has a phase evaluation device 406 for evaluating the phase of the received signal. The evaluation of the amplitude can be used for data evaluation and / or distance evaluation, the phase can be used for position evaluation.

[0062] The signal transmission device 420 of the signal adaptation device 400 also has an overvoltage protection device 407, a weakening device 408 and an adaptable filter device 409. The adaptable filter device 409 can generate excitation pulses and / or test pulses, for example direct current pulses for the adaptable filter device 409, by means of the excitation device 410.

[0063] The overvoltage protection device 407 is adapted to the operating frequency of the inductive energy transfer system 100, for example 85 kHz, and is designed to discharge high voltages that can be incorrectly coupled into the antenna 302ax generated by the inductive energy transfer system. During energy transfer, 1000 V or more can be induced in the POS antenna 302ax, since the POS antenna 302ax can have a POS winding that is wound around the ferrite 303 and thus can cause the field lines generated by the primary coil LI to run completely through the winding 302ax and generate a voltage. However, this induced voltage is too high for the structural elements of the evaluation circuit, so that the evaluation circuit must be protected against destruction.

[0064] The signal transmission device 420 is designed so that the phase of the electromagnetic signal is not changed substantially. The phase is evaluated by the evaluation circuit 402 in order to carry out a position determination.

[0065] Furthermore, the signal transmission device 420 is designed to adapt the amplitude of the electromagnetic signal to a characteristic that can be preset by the evaluation circuit 402 and / or the evaluation unit 307, for example, so that different signal strengths in the near field and / or far field can be taken into account.

[0066] The received electromagnetic signal, for example the position signal POS, can be further given on the evaluation connection 404 to the evaluation circuit 402.

[0067] Figure 5A circuit configuration for the overvoltage protection 407 according to an exemplary embodiment of the application is shown. In this case, the antenna 302ax is connected with the capacitor Cl' and the attenuating mechanism 503 of the attenuating device 408. The attenuating mechanism 503 for the attenuation adaptation is connected with the antenna 302ax. On the attenuating element, the voltage U_x drops. The antenna 302ax receives the voltage U_ind. Furthermore, the first diode 501 connects the terminal of the capacitor Cl' with the supply voltage Vcc and the second diode connects the same terminal of the capacitor Cl' with the reference potential.

[0068] Figure 6 A replacement circuit configuration for the overvoltage protection 407' according to an exemplary embodiment of the application is shown. The structure of the circuit from Figure 6 corresponds essentially to the structure from Figure 5 . However, the first diode 501' and the second diode 502' are connected anti-parallel, so that the anode of the first diode 501' is connected with the first input 504 of the attenuating device 408 and the terminal of the capacitor Cl' and the cathode is connected with the second input 505 of the attenuating device 408. The anode of the second diode 502' is connected with the second input 505 of the attenuating device 408 and the cathode is connected with the first input 504 of the attenuating device 408 and the terminal of the capacitor Cl'. Neither of the diodes 501', 502' is connected with the supply voltage or the reference potential.

[0069] Figure 5 and 6 two embodiments of a Weg clampen for the high voltage U_ind are shown, which can occur in the antenna 302ax.

[0070] According to Figure 5 , the capacitor Cl' of the high voltage protection circuit 407 for the induced voltage U_ind forms an impedance, which can be calculated according to the following formula:

[0071]

[0072] Z_longitudinal is the longitudinal impedance (series impedance) and ω_field corresponds to the frequency of the disturbing radiation, for example 85 kHz.

[0073] Since the input impedance 503 of the attenuating device 408, on which the voltage U_x is applied, is relatively high, the longitudinal impedance Z_longitudinal of the capacitor Cl' forms a voltage divider with the input impedance Z_x 503 of the attenuating circuit 408 and the subsequent circuit components. As long as the input voltage U_x of the attenuating circuit 408 is below the breakdown voltage of the diodes 501', 502', the diodes 501', 502' are not conducting and the voltage U_ind is applied to the input 504, 505 of the attenuating device 408.

[0074]

[0075] Exceeding the feed voltage Vcc plus the diode forward voltage (Vcc + Vforward) then the current induced in the antenna 302ax flows through the diodes 501, 502 out into the feed Vcc.

[0076] Now, the Cl', the diodes and the feed have to be designed in such a way that the current flowing during charging I_duration_charging = (U_ind - diode forward voltage - Vcc) / Z_forward, that is to say the current flowing during charging, does not cause a malfunction. The current I_duration_charging is defined by the Cl and the induced voltage U_ind.

[0077] An overvoltage protection can be necessary because in the inductive charging system 100 a positioning system 302, 307 is used in the vicinity of an extremely strong magnetic field 106. Thus, the magnetic field 106 of the energy transfer can destroy the sensitive receiving circuit 402 of the positioning determination sensor 302ax because of the high induced voltage U_ind.

[0078] Instead of a clamping diode which represents a low-ohmic parallel path with respect to the sensitive measuring circuit, in combination with a resistive impedance for limiting the current, for example a resistor, a PTC, a semiconductor component, etc., the overvoltage protection 407 is essentially not provided with a resistive element but with a capacitive element. Thereby it can be avoided that the resistive current-limiting element either causes high losses of several watts during inductive charging or causes an undesired high signal attenuation during the positioning of the vehicle. The capacitive element also avoids an expensive control circuit and costs which would be necessary in the case of using a resistive current-limiting element with a variable impedance, for example a MOSFET.

[0079] Correspondingly, the use of a non-resistive element as a current-limiting element, that is to say an element which only causes apparent power, is provided. In other words, as a current-limiting element an element with a complex impedance should be used, the real part of which is zero and the imaginary part of which is not equal to zero, that is to say real {Z} = 0; imaginary {z} ≠ 0. By omitting the high losses the impedance of the non-resistive current-limiting element, for example a capacitance, can be greatly reduced, thus the element is not destroyed by the high voltage and less loss power is generated.

[0080] By the occurrence of different signal strengths, for example in the near field and in the far field, the signal transmission device 400 should be provided in such a way that the receiving sensitivity can be switched over so that the dynamic range of the signal on the analog-digital-converter (ADC) of the evaluation device 402 is limited to a value so that the entire dynamic range is used. However, the attenuating switching over should not amplify the bandwidth of the filter structure 409 too much because otherwise the interference can no longer be sufficiently suppressed.

[0081] It is to be avoided that the LC tank is attenuated by means of a switchable resistance in resistive form in order to avoid an undesired strong bandwidth amplification. The bandwidth amplification can have a negative effect on the phase progression in particular, so that the position or the influence on it can no longer be derived from the positioning signal.

[0082] The use of a switchable capacitance is also to be avoided in order to achieve a signal level drop based on the principle of a capacitive voltage divider, since a shift of the resonance frequency of the filter 409 can occur thereby, which in turn leads to a deterioration of the quality of the positioning signal and to an inaccurate position determination.

[0083] The signal adaptation device 400 provides for the switching on and / or off of a capacitance Cd to the series tank 701 in order to change the attenuation. It is possible to use the series tank already present in the energy transmission system and / or in the positioning system doubly if necessary. The capacitance is arranged at a specifically determined point of the series tank 701 which is present in any case. With a suitable design of the participating components, it is thus possible to achieve the attenuation substantially without an undesired strong bandwidth amplification and without a shift of the resonance frequency.

[0084] Figure 7 A series tank 701 without switched attenuation device is shown according to an exemplary embodiment of the application. The series tank 701 has a capacitance C1', a resistance R and a coil L and is connected to a parallel tank 702 with a resistance Rp, a coil Lp and a capacitor Cp. The attenuation device 408 comprises such a series tank 701, for example. Figure 7 and 8 C1' corresponds to C1' from Figure 6 The series tank 701 receives a signal on the input 504' from the antenna 302ax which is not shown in Figure 7 The signal is guided via the parallel tank and is continued in the direction of the evaluation device 402 on the output 506'.

[0085] Figure 8 A series tank 701 with switched attenuation device 801 is shown according to an exemplary embodiment of the application. The series tank substantially corresponds to the tank from Figure 7 However, an additional capacitor Cd is switched in via the attenuation switch device 801 which has a switch and an actuation source which is shown as a voltage source in the illustration from Figure 8 The attenuation switch device 801 is connected to the reference potential like the parallel tank 702.

[0086] Figure 8 In the switching mode shown in

[0087] Figure 9 The frequency characteristics of different attenuation devices according to an exemplary embodiment of the application are shown. In this case, the frequency is shown on the abscissa in a logarithmic scale. The attenuation in dB is shown on the ordinate.

[0088] C1' is a non-ohmic current-limiting element. The clamping diodes 501, 502, 501', 502' are not drawn in Figure 7 and 8 . They play a subordinate role for the frequency characteristic analysis. The curve 901 shows the course which is obtained when neither the coil L nor the resistor R2 is used in the series oscillation circuit 701. The course of the curve 901 shows that, although a desired resonance 910 is formed at the resonance frequency 125 kHz, which is used for the POS signal, for example a keyless entry system signal. However, a small filter action is shown for frequencies above 125 kHz, where the curve 901 does not drop and remains at approximately the same level. The reason for this is that the current-limiting capacitor together with C1' of the oscillation circuit 701 forms a capacitive voltage divider which determines the maximum attenuation at high frequencies.

[0089] The curve 902 shows the frequency characteristic of the circuit as in Figure 7 , but without R2, in whose case the inductance L is added to the signal path in order to better attenuate high-frequency interference. Although a higher-frequency attenuation is carried out, this inductance forms a series oscillation circuit with the current-limiting capacitor C1' so that a new, undesired resonance 911 occurs at approximately 135 kHz.

[0090] The curve 903 shows the frequency characteristic at the output 506' of the circuit from Figure 7 . It can be recognized that the undesired resonance 911 is eliminated by means of the resistor R2 in series with L and C1'. Thus, this circuit can be used for far-field attenuation if the positioning signal POS is very weak.

[0091] The curve 904 shows a curve which uses the circuit according to Figure 8The switchable capacitance Cd is obtained. In this case, the series resonant circuit 701 which is present in any case in the energy transfer system 100 is used twice in order to eliminate the problem of the undesired high bandwidth. For this purpose, the switch 801 is positioned in such a way that it switches the capacitance Cd between the resistance R2 and the capacitor Ci'. Since the capacitance Cd is used instead of a resistive element or resistance, the capacitance Cd, with a suitable selection of the capacitance of this capacitance, reduces the resonance frequency of the series resonant circuit 701 in the desired amount, so that the resulting attenuation minimum 912 falls just on the signal frequency in the case of 125 kHz, for example. By a suitable selection of Cd, the attenuation can be selected in such a way that the signal strength on the evaluation circuit lies in the desired range.

[0092] By the selection of the location and the corresponding dimensioning and the selection as a resistive element, the high-frequency interference is suppressed even more significantly (20 dB). At the same time, the signal level is reduced as desired. As a result, the circuit can be used for near-field attenuation if the positioning signal POS is particularly strong. The resistance R2 can also be located or built in at a different location.

[0093] The curve 905 shows the course of the filter structure, in which a switchable resistance is built in at a location different from Cd, for example between the coil L and the parallel resonant circuit 702. This switchable resistance, although it increases the signal attenuation when required, if, for example, the near field should be used, as can be derived from the deeper peak 912 with respect to 910. However, the resistance reduces the quality of the parallel resonant circuit 702 and thereby increases its bandwidth and does not reduce the signal as strongly to higher frequencies as curve 904. As can be derived from the course 905, the signal attenuation in the case of 125 kHz is increased as desired, but the interference signal suppressed in the case of, for example, 500 kHz is only slightly increased because of its large bandwidth.

[0094] Thus, according to the arrangement Figure 7 and 8 a transition of the attenuation between the peaks 910 and 911 is caused without an excessive bandwidth enlargement or a shift of the resonance frequency.

[0095] In order to be able to filter out interference, bandpass filter structures are provided in the filter 409. These bandpass filter structures are subject to component scatterings due to the amplitude evaluation device 405 and the phase evaluation device 406, which lead to errors in the amplitude measurement and in particular in the phase measurement. Here, the capacitance and / or the inductance of the LC resonant circuit is implemented in a regulatable manner, for example by switching on and off of the capacitance.

[0096] However, there is also a temperature dependency of the filter elements, so that a one-time adjustment in the production line is not sufficient, i.e. the energy transmission system 100, in particular its positioning system 302, 307, 401, should autonomously be able to perform an oscillation loop adjustment when required, for example before each vehicle positioning process.

[0097] For this adjustment, the signal zero-crossing detector present in the positioning system for the signal phase measurement is used in a dual use, in which the signal zero-crossing detector is also used to measure the oscillation duration of the natural resonance of the LC oscillation loop 701, 702.

[0098] At the start of this measurement, the LC oscillation loop 701, 702 is excited sufficiently, for example by switching on and off a direct current source, which is connected to the LC oscillation loop 701, 702 and brings the LC oscillation loop 701, 702 to oscillation. In this way, the filter can be adapted or improved in order to compensate for disturbances that have been identified.

[0099] The adaptation of the filter can be used, for example, for a reception filter, for example a reception noise filter. In order to reduce reception noise or reception noise, the filter, in particular a bandpass, is set to the evaluation circuit 402. Interferences can thus be filtered out. The filter should have a quality that is as small as possible, because otherwise the signal cannot die away gradually and the data evaluation of the positioning signal becomes difficult. The data evaluation 405 can decode the content in the positioning signal in order to appear data and work in parallel to the amplitude evaluation 405. The quality Q should be between 2 and 100. Since the filter structure contains components that are subject to scattering, the filter must be adapted.

[0100] An oscillation loop with a high quality has a sharp phase step at the resonance frequency. An oscillation loop with a low quality, in contrast, has a broad phase step. A broad phase step can cause the phase information to no longer be able to be reconstructed well with the phase evaluation device 406 and thus the position to no longer be able to be determined reliably. Therefore, for the correct phase measurement of the positioning signal, it is necessary to tune the filter 409 very precisely to the positioning signal operating frequency of, for example, 125 kHz, since the quality should be high for the phase information for sensitivity reasons.

[0101] If the filter 409 is not adapted to the operating frequency, the filter changes the phase of the positioning signal on the evaluation circuit 402, 406, whereby a misinterpretation of the pose determination of the CPE 104 and the GPE 105 and false coordinates can occur. The resonance frequency of the filter can also be set near the operating frequency of the positioning signal. In this case, the phase is no longer strongly dependent on the component scattering, but the filter no longer works very well.

[0102] The component scatter can be compensated in that the filter 409 is excited to oscillation with a pulse through the excitation device 410 and uses the phase measurement circuit 406 which is anyway required for the position determination in order to determine the resonance frequency, for example through a zero crossing measurement. The filter 409 can then be adapted by switching on and / or off the capacitors such that the component tolerances are compensated.

[0103] Figure 10 A flow chart of a method for adapting an adaptable filter device 409 of a signal adapting device according to an exemplary embodiment of the application is shown.

[0104] Starting from an idle state S1000, in a state S1001 the adaptable filter device 409 is excited with an excitation pulse, for example a short DC pulse. In a state S1002 a measurement of the phase is carried out, for example through a phase measurement device 406 of an inductive energy transfer system, for example additionally used for evaluating the positioning signal, to determine the period duration and the phase of the filter 409. In a state S1003 the adaptable filter device 409 is adapted by switching on and / or off of at least one capacitor and / or inductor and / or capacitor array towards the filter device 409. The method ends in an idle state S1004.

[0105] The switchable components can also be seated or arranged in the evaluation unit 405 or be embodied as structural elements which are switchably accessible discretely. These structural elements can for example be connected in parallel to the Cp in the Figure 7

[0106] It is additionally pointed out that "comprising" and "having" do not exclude further elements or steps and "a" or "an" does not exclude plural. Furthermore it is pointed out that features or steps which have been described with reference to one of the above embodiments can also be used in combination with other features or steps of other of the above described embodiments. Reference signs in the claims do not limit their scope.​

Claims

1. A signal adaptation device (400) for an evaluation circuit (402) for evaluating an electromagnetic signal for operation in an inductive energy transfer system, the signal adaptation device having: a signal transfer device (420) having: an antenna connection (403) for connecting a receiving antenna (302ax), which is arranged to receive an electromagnetic signal from the receiving antenna, the electromagnetic signal having an amplitude and a phase; an attenuation device (408) for connecting the antenna connection (403), wherein the attenuation device (408) is arranged to attenuate the electromagnetic signal such that the amplitude is adapted to a characteristic which can be preset by the evaluation circuit; wherein the attenuation influences the phase of the electromagnetic signal; an adaptable filter device (409) for connecting the attenuation device (408), the adaptable filter device (409) having a structure which is arranged to switch on and / or off one or more capacitors and / or inductance components in order to adapt the phase influenced by the attenuation of the electromagnetic signal by the attenuation device (408) to the phase of the electromagnetic signal received by the antenna connection (403) such that the phase of the electromagnetic signal is essentially not changed, and an evaluation connection for connecting the adaptable filter device (409) and the evaluation circuit, which is arranged to provide the attenuated and adapted electromagnetic signal from the adaptable filter device (409) to the evaluation circuit for evaluation. signal transmission device (420), wherein the signal transfer device (420) further having an overvoltage protection device (407) connected between the antenna connection (403) and the attenuation device (408), wherein the overvoltage protection device (407) is adapted to an operating frequency of the inductive energy transfer system such that a high voltage generated by the inductive energy transfer system is derived. the attenuation device (408) being further arranged to form a voltage divider with the overvoltage protection device (407) connected between the antenna connection (403) and the attenuation device (408). the attenuation device being switchable between a near field characteristic and a far field characteristic of the electromagnetic signal. the attenuation device having a capacitive attenuation element (Cd). the capacitive attenuation element (Cd) forming a capacitive voltage divider and / or a capacitive attenuation element together with the overvoltage protection device (407).

2. The signal adapting device (400) according to claim 1, wherein the attenuation device being arranged to attenuate signals above and / or below the frequency of the electromagnetic signal more strongly than signals at the frequency of the electromagnetic signal.

3. The signal adapting device according to claim 1, wherein 8. The signal adaptation device according to claim 1, the adaptable filter device (409) being further arranged to compensate for deviations of elements in the filter structure of the adaptable filter device (409).

4. The signal adaptation device of claim 3, wherein, the adaptable filter device (409) using a phase measuring device of the inductive energy transfer system for adapting the phase and / or for compensating for the deviations of the elements.

5. The signal adaptation device of claim 3, wherein, ​ 6. The signal adaptation device of claim 5, wherein, ​ 7. The signal adaptation device of claim 3, wherein, ​ ​ 9. The signal adaptation device of claim 8, wherein, ​ 10. The signal adapting device according to claim 1, wherein, The electromagnetic signal is a positioning signal.

11. The signal adapting device according to claim 1, wherein The evaluation circuit is configured to evaluate the amplitude and / or the phase of the attenuated and adapted electromagnetic signal.

12. A method for adapting an adaptable filter device of a signal adapting device according to claim 8, having: exciting the adaptable filter device (409) with an excitation pulse; measuring the phase of the adaptable filter device (409) with a phase measuring device of the inductive energy transfer system; adapting the adaptable filter device (409) by switching on and / or off at least one capacitor and / or capacitor array of a capacitor and / or inductance assembly relative to the filter device.

13. The signal adaptation device of claim 9, wherein, The phase measuring device is a zero-crossing measuring device.

14. The signal adaptation device of claim 10, wherein, The positioning signal is a keyless entry system signal.

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