An antenna device and a method of operating an antenna device

Abstract

An antenna device and a method of operating an antenna device. The invention relates to an antenna device, wherein the antenna device (1) comprises a voltage source (3), a first inductive antenna element (L1), a second inductive antenna element (L2) and at least one capacitive element (C), wherein the voltage source (3) is electrically connected in parallel to a series connection of a first circuit portion comprising at least the first inductive antenna element (L1) and a further circuit portion comprising a parallel connection of a first sub-portion of the further circuit portion comprising the at least one capacitive element (C) and a further sub-portion of the further circuit portion comprising at least the second inductive antenna element (L2); and a method of operating an antenna device.

Description

[0001] The present invention relates to an antenna device, particularly an antenna device for generating signals for positioning purposes, and more specifically to a device for positioning the vehicle-side secondary winding structure relative to the primary winding structure of a positioning system for the purpose of transmitting induced power to the vehicle.

[0002] Electric vehicles, particularly rail vehicles and / or highway vehicles, can operate using electrical energy transmitted via inductive power transmission. Such vehicles may include a so-called receiving device adapted to receive alternating electromagnetic fields and generate alternating current (AC) through electromagnetic induction. This receiving device may include or provide a so-called secondary winding structure. Furthermore, such vehicles may include a rectifier adapted to convert alternating current (AC) to direct current (DC). DC can be used to charge a traction battery or to power a motor. The rectifier converts the AC power supplied by the receiving device into DC power.

[0003] Inductive power transmission is typically performed using primary and secondary units. The primary unit generates an alternating electromagnetic field through a primary winding structure, and the secondary unit includes a receiving device for receiving the electromagnetic field. The primary and secondary units may, for example, each include a set of three-phase windings, providing the aforementioned primary and secondary winding structure. One set of windings of the primary unit may be mounted on the ground (primary winding structure) and may be powered by a roadside power converter (WPC). One set of windings of the secondary unit (secondary winding structure) is mounted on the vehicle. For example, for some trams located under freight cars, a second set of windings may be connected under the vehicle. The primary winding set may also be referred to as the primary side, and the secondary winding set may be referred to as the secondary side. The primary and secondary sides may be part of a high-frequency transformer to transmit electrical energy to the vehicle. This can be done in both static (when the vehicle is not moving) and dynamic (when the vehicle is moving) states.

[0004] Inductive power transmission typically requires the correct positioning of the vehicle-side secondary winding structure relative to the primary winding structure to maximize power transmission while meeting safety requirements and ensuring electromagnetic compatibility.

[0005] The relative positions can be determined, for example, based on the relative positions between the antenna device that generates the positioning signal and the receiving antenna device that receives the positioning signal, wherein the relative positions between the devices are determined based on the signal characteristics of the received positioning signal. In this case, the antenna device that generates the positioning signal can be a primary-side antenna device, and the receiving antenna device can be a secondary-side antenna device, or vice versa.

[0006] WO2017 / 064326A1 discloses an inductive power transmission unit, wherein the inductive power transmission unit includes at least one winding structure or at least one magnetic flux guiding device, and wherein the inductive power transmission unit further includes at least one antenna element, wherein at least one part of the at least one magnetic flux guiding device is part of the antenna element.

[0007] Document WO2017 / 042364A1 discloses a system for determining the relative position and / or orientation between the primary winding structure and the secondary winding structure of an inductive power transmission system.

[0008] US 7,454,170 B2 discloses an inductive transmission system for inductively transmitting power and full-duplex data signals between a first device and a second device. The transmission system includes a bidirectional inductive channel between the two devices, a transmitter for transmitting a power signal of a first frequency from the first device to the second device via the inductive channel, a first modulation device for modulating the first data signal at a first modulation frequency, and a second modulation device for modulating a second data signal at a second modulation frequency. Furthermore, the transmitter transmits the modulated first data signal from the first device to the second device via the inductive channel, and transmits the modulated second data signal from the second device to the first device via the inductive channel. The first modulation frequency and the second modulation frequency are at least twice the distance between them.

[0009] WO 2011 / 127455 A2 describes wireless charging and wireless power alignment of vehicle-related wireless power antennas.

[0010] WO 2014 / 023595 A2 discloses a vehicle and an inductive charging unit, wherein the inductive charging unit includes a primary coil and the vehicle includes a secondary coil. Furthermore, at the charging position, the secondary coil is located within a preferred spatial position range relative to the primary coil; therefore, to set the charging position, the system determines the orientation representing the time-related spatial position of the secondary coil relative to the primary coil using electromagnetic distance and angular measurements obtained using triangulation. The system detects at least one portion of the travel direction along which the orientation of the charging position can be approached based on the position and the charging position.

[0011] The technical problem is to provide an antenna device and a method of operating the antenna device that allows for the reliable and accurate generation of a positioning signal with predetermined, desired characteristics, requiring only a small number of components.

[0012] The subject matter having the features of claims 1 and 14 provides a solution to the aforementioned technical problem. The technical subject matter having the features of the dependent claims provides further advantageous embodiments.

[0013] This paper proposes an antenna device, particularly for generating a positioning signal. The positioning signal can be used to perform a method for determining the relative position and / or orientation between a unit including the antenna device and a positioning signal receiving unit. These units can be, for example, units for a system for inductively transmitting power to a vehicle, particularly secondary and primary units. In this case, the antenna device can be a primary-side antenna device, where the positioning signal receiving device is a secondary-side device. Alternatively, the antenna device can be a secondary-side device, where the positioning signal receiving device is a primary-side device. The relative position and / or orientation between the antenna device for generating the positioning signal and the positioning signal receiving device can be determined, for example, based on the positioning signal received by the receiving device, particularly based on the signal characteristics of the received positioning signal. The signal characteristics can be, for example, the spectral power of the positioning signal. The relative position can be determined, for example, in a secondary-side coordinate system or a primary-side coordinate system.

[0014] The relative position and / or orientation can be determined, for example, by a secondary-side control unit or a primary-side control unit. The control unit may, for example, include one or more microcontrollers.

[0015] The antenna device includes a voltage source, particularly for generating AC (alternating current) voltage. The AC voltage may have predetermined characteristics, particularly a predetermined frequency. At least one characteristic of the voltage source, particularly the AC voltage, may be controlled by a control unit, which may, for example, also be part of the antenna device. The control unit may be provided by at least one microcontroller and / or at least one integrated circuit.

[0016] Furthermore, the antenna device includes a first inductive antenna element and a second inductive antenna element. The inductive antenna elements can be provided, for example, by an antenna winding or an antenna coil. The inductive antenna element is a component used to generate an electromagnetic field that provides a positioning signal. A first positioning signal can be generated using the first inductive antenna element. A second positioning signal can be generated using the second inductive antenna element.

[0017] In addition, the antenna device includes at least one capacitive element, particularly a capacitor.

[0018] Furthermore, a voltage source is connected in parallel to the series connection between the first circuit section and the other circuit section. The first circuit section includes at least a first antenna element. The other circuit section includes a parallel connection between a first sub-section of the other circuit section and another sub-section of the other circuit section. The first sub-section includes at least one capacitor element, and the other sub-section includes at least one second antenna element.

[0019] The voltage source, also known as the drive source, drives a circuit provided by a series connection of a first circuit section and another circuit section. If an AC voltage is applied to this circuit, the inductive antenna element generates an electromagnetic field. The voltage falling between the terminals of the two antenna elements will have a predetermined phase shift, specifically a 90° phase shift. This results in the generation of a positioning signal with said predetermined phase shift.

[0020] Generating two positioning signals with a predetermined phase shift advantageously allows for robust and accurate determination of the relative position and / or orientation between the antenna device generating the positioning signals and the receiving device receiving the positioning signals. Specifically, the predetermined phase shift information can be used to determine the relative position and / or orientation. Furthermore, the antenna device proposed herein advantageously allows for the generation of positioning signals, for example, electromagnetic fields having significant portions oriented in different (particularly two or more) spatial directions, where the spatial directions can be perpendicular to each other. More specifically, the antenna device advantageously allows for the generation of circular or elliptical electromagnetic fields (if the time-varying direction of the electromagnetic field is taken into account). This simplifies the robust and accurate determination of the aforementioned relative position and / or orientation.

[0021] In other words, this paper provides a two-dimensional (2D) antenna device that allows for the accurate generation of positioning signals with a predetermined phase shift using a small number of components (in particular, a single voltage source).

[0022] The frequency of the driving AC voltage can be equal to a predetermined resonant frequency or such that its deviation from the predetermined resonant frequency does not exceed a predetermined amount. The predetermined resonant frequency can, for example, be the resonant frequency of a circuit provided by a series connection of a first circuit section and another circuit section. This advantageously allows for the generation of a positioning signal with reduced reactive power, i.e., actively generated positioning signal.

[0023] In another embodiment, the reactance of the first circuit portion is equal to the reactance of the first sub-portion of the other circuit portion. Additionally or alternatively, the reactance of the first circuit portion is equal to the reactance of another sub-portion of the other circuit portion. Additionally or alternatively, the reactance of the first sub-portion of the other circuit portion and the reactance of the other sub-portion of the other circuit portion may also be equal.

[0024] In particular, the absolute value of the reactance of the first circuit section may be equal to the absolute value of the reactance of the first subsection of another circuit section and / or equal to the absolute value of the reactance of another subsection of another circuit section.

[0025] This equality can be provided, for example, at one or more predetermined frequencies, particularly the drive frequency of the drive voltage. In this case, the current flowing through the second inductive antenna element is directly proportional to the drive voltage and inversely proportional to the reactance of the capacitive element, regardless of the resistance in the first sub-section, particularly the resistance of the second inductive antenna or the resistance of the additional resistive element. Therefore, this reduces the current level supplied by the voltage source. The current equals:

[0026] I=Ud / X(Formula 1)

[0027] Where I represents the current flowing through the second inductive antenna element, Ud represents the driving voltage, and X represents the reactance of another sub-part of another circuit section.

[0028] If the aforementioned reactances or their absolute values ​​are equal, the currents flowing through the first and second antenna elements will be phase-shifted by 90°. Therefore, the antenna device can provide an elliptical, and particularly circular, electromagnetic field, especially when the central axis of the first antenna element is oriented perpendicular to the central axis of the second antenna element.

[0029] In another embodiment, the antenna device includes at least one resistive element, particularly a resistor. Furthermore, another sub-section of another circuit section includes a series connection of at least one second antenna element with at least one resistive element. The resistive element may be different from the second antenna element.

[0030] Providing an additional resistive element advantageously allows setting the ratio between the current flowing through the first inductive antenna element and the current flowing through the second inductive antenna element, and vice versa. Setting the ratio allows setting the signal strength or amplitude of different portions of the generated electromagnetic field, particularly portions oriented in different spatial directions. This ratio can be set, for example, to a value in the range of 0 (excluding) to infinity (excluding), particularly from 0.1 to 10.

[0031] In another embodiment, the antenna device includes at least one additional compensation capacitor element. This additional compensation element may be different from the capacitor element disposed in the first sub-section of another circuit section.

[0032] By using at least one additional compensation capacitor element, the resonant frequency of the antenna drive circuit can be adapted to, for example, the characteristics of a voltage source. For instance, only selected antenna elements with a limited range of characteristics may be available / usable. The compensation capacitor element can be selected such that the resonant frequency of the drive circuit with said selected antenna element is adapted to (in particular equal to) the range of drive frequencies available from the voltage source. This advantageously allows the drive circuit to operate in an energy-efficient manner.

[0033] In another embodiment, the first circuit section includes a compensation capacitor element connected in series with the first antenna element. Alternatively or additionally, another subsection of another circuit section includes a compensation capacitor element connected in series with the second antenna element. This advantageously allows for simple adjustment of the resonant frequency of the drive circuit.

[0034] In another embodiment, the antenna device includes at least an additional compensating inductor. This additional compensating inductor reduces or eliminates the influence of external electromagnetic fields on the operation of the drive circuit. The external electromagnetic field can be, for example, an electromagnetic field generated by the primary winding structure for induced power transmission. Specifically, the external electromagnetic field differs from the electromagnetic field providing the positioning signal. The external electromagnetic field may induce a voltage in the additional compensating inductor, which is used to reduce another induced voltage in the drive circuit caused by the external electromagnetic field.

[0035] This advantageously increases the reliability and stability of the generated positioning signal.

[0036] Preferably, the additional compensating inductor and antenna elements are designed and / or arranged such that there is no mutual coupling between the inductor elements or that the mutual coupling is less than a predetermined low threshold. This can be achieved, for example, by separating at least one additional compensating inductor from the inductive antenna element by a predetermined distance. However, other methods may also be used to achieve low mutual coupling. This advantageously reduces undesirable attenuation of the positioning signal by compensating the inductor or the signal generated by the compensating inductor.

[0037] In another embodiment, the first circuit portion includes a series connection of a compensating inductor element to a first antenna element. Alternatively or additionally, another sub-portion includes a series connection of a compensating inductor element to a second antenna element. In this case, the first circuit portion may include a series connection of a compensating inductor element, a compensating capacitor element, and the first antenna element. Furthermore, the other sub-portion may include a series connection of a compensating inductor element, a compensating capacitor element, and / or a resistive element to the second antenna element. This advantageously allows for reliable and accurate reduction of the effects of external electromagnetic fields.

[0038] In another embodiment, the antenna device includes at least two compensating inductor elements, wherein the at least two compensating inductor elements are provided by coils wound in opposite directions, specifically in opposite directions relative to each other. This can mean that the compensating inductor elements are configured and / or arranged within the drive circuit such that the voltage induced by the external electromagnetic field in the first compensating inductor element is opposite to, but has equal absolute values, and the sum of the voltages is zero or approximately zero. This advantageously allows for a simple yet reliable and robust reduction of the influence of external electromagnetic fields on the drive circuit.

[0039] In another embodiment, the antenna device includes at least one magnetically conductive element, wherein at least one antenna element is wound around at least a portion of the magnetically conductive element. The magnetically conductive element may be, for example, a ferrite element, more specifically a ferrite rod or ferrite bar. In this case, at least one antenna element may be a ferrite rod antenna. This advantageously allows for the generation of strong positioning signals and the attainment of a compactly designed antenna device.

[0040] In another embodiment, a first antenna element and another antenna element are wound around different portions of a magnetically conductive element. In this case, the antenna device may include a single magnetically conductive element, wherein the first antenna element and another antenna element are wound around different portions of the single magnetically conductive element. This advantageously reduces the number of elements in the antenna device proposed herein, thus making the manufacture of the antenna device cost-effective and reducing the construction space requirements.

[0041] In an alternative embodiment, the antenna device includes a first magnetic element and a second magnetic element, wherein the first antenna element is wound around the first magnetic element and the second antenna element is wound around the second magnetic element. In this case, the first magnetic element and the second magnetic element can be separate elements.

[0042] In another embodiment, the magnetic element is a magnetic element of a secondary unit of the system for inductive power transmission. The magnetic element can be a flux guiding device for guiding the electromagnetic field flux used for inductive power transmission. This advantageously allows for further reductions in manufacturing costs and build space requirements, because the magnetic element used for guiding the electromagnetic field flux used for inductive power transmission also guides the electromagnetic field flux providing positioning signals.

[0043] In another embodiment, the central axis of the first antenna element is not parallel to the central axis of the other antenna element. This means that the angle enclosed by the central axes can be selected from 0° (excluding) to 180° (excluding). Preferably, the central axis of the first antenna element and the central axis of the other antenna element can be perpendicular to each other. In this case, the central axis of the magnetic element or the central axis of the portion of the magnetic element around which the first and other antenna elements are wound can also be non-parallel, particularly perpendicular to each other.

[0044] This advantageously allows for the robust and reliable generation of 2D electromagnetic fields for positioning purposes.

[0045] This document also proposes a method of operating an antenna device according to one of the embodiments described in this disclosure. In this method, an alternating current (AC) voltage is generated by a voltage source. The AC voltage may have a predetermined frequency. In particular, the AC voltage may also be referred to as a driving voltage, which may be a sinusoidal or any other periodic voltage, such as a rectangular or triangular voltage.

[0046] This method advantageously allows the generation of positioning signals with desired characteristics, particularly circular or elliptical positioning signals, for accurately and robustly determining the relative position and / or orientation between the proposed antenna device and a receiving device for receiving the positioning signal.

[0047] In another embodiment, the frequency of the generated voltage (driving voltage) is equal to the resonant frequency of the series connection between the first circuit section and the other circuit section. This advantage and corresponding advantages have been disclosed above.

[0048] This paper further describes a method for determining the relative position and / or orientation between the proposed antenna device and a receiving device for receiving a positioning signal generated by the proposed antenna device. The antenna device may be fixedly arranged in position and / or orientation relative to the primary or secondary winding structure of the system for inductive power transmission, wherein the receiving device is fixedly arranged in position and / or orientation relative to the remaining winding structure. In this case, the method also allows for determining the relative position and / or orientation between the primary and secondary winding structures of the system for inductive power transmission, which is also described herein.

[0049] A receiving device for receiving a positioning signal generated by the antenna device proposed herein may have the same features as the antenna device proposed herein for generating the positioning signal. In particular, it may be designed to be similar to or identical to the antenna device proposed herein for generating the positioning signal. Therefore, all features outlined in this disclosure regarding the proposed antenna device may be features of the receiving antenna device. A position determination system is further described herein, comprising the antenna device proposed herein for generating a positioning signal and the receiving device. This system allows determination of the relative position and / or orientation between the antenna device proposed herein and the receiving device for receiving the positioning signal generated by the antenna device proposed herein. The system may also include a control unit, for example, a microcontroller or integrated circuit. The control unit may determine the relative position and / or orientation, for example, based on the output signal of the receiving device.

[0050] The present invention will now be described with reference to the accompanying drawings.

[0051] The attached diagram shows:

[0052] Figure 1 This is a schematic diagram of a magnetically conductive element with two inductive antenna elements.

[0053] Figure 2 This is a schematic circuit diagram of an antenna device according to a first embodiment of the present invention.

[0054] Figure 3 This is a schematic circuit diagram of an antenna device according to a second embodiment of the present invention.

[0055] Figure 4 This is a schematic circuit diagram of an antenna device according to a third embodiment of the present invention.

[0056] Figure 5 This is a schematic circuit diagram of an antenna device according to a fourth embodiment of the present invention.

[0057] Figure 6 This is a schematic block diagram of an antenna device for generating positioning signals and a receiving device for receiving positioning signals.

[0058] In the following text, the same reference numerals denote the same or similar technical features.

[0059] Figure 1 A schematic diagram of a first inductive antenna element L1 and a second inductive antenna element L2 is shown. The first and second inductive antenna elements L1 and L2 are provided by a winding structure, particularly a coil. The diagram further shows a magnetic element 2, particularly a ferrite element. The ferrite element 2 has a cross shape. Antenna elements L1 and L2 are wound around different portions of the magnetic element 2. Specifically, the inductive antenna elements L1 and L2 are arranged such that the central axis CL1 of the first inductive antenna element and the central axis CL2 of the second inductive antenna element L2 are perpendicular to each other. Furthermore, the corresponding inductive antenna elements L1 and L2 are wound around portions of the magnetic element 2, particularly their central axes, which are also perpendicular to each other.

[0060] Figure 1 One embodiment is shown in which different inductive antenna elements L1, L2 are wound around a single magnetic element. However, the inductive antenna elements L1, L2 can also be wound around a single magnetic element.

[0061] The magnetic element 2 can be a magnetic element of a secondary unit with a secondary winding structure for a system used to transmit inductive power to a vehicle, or a primary unit with a primary winding structure. In such a secondary or primary unit, the magnetic element can be used to guide the electromagnetic field flux used for transmitting inductive power, particularly the electromagnetic field generated by the primary winding structure or received by the secondary winding structure.

[0062] Figure 2A schematic circuit diagram of an antenna device 1 according to a first embodiment of the present invention is shown. The antenna device 1 includes a voltage source 3, a first inductive antenna element L1, a second inductive antenna element L2, a capacitor element C, and a resistor element R. The first inductive antenna element L1 is arranged in a first circuit section and is connected in series to a second circuit section or another circuit section, which includes the first circuit section and another circuit section. The other circuit section includes a first sub-section and a second sub-section connected in parallel. The first sub-section includes the capacitor element C, and the second sub-section includes the second inductive antenna element L2 connected in series with the resistor element R. The first sub-section and the other sub-section of the other circuit section are connected in parallel.

[0063] Voltage source 3 is a voltage source used to generate AC voltage, especially periodic or harmonic voltage. The voltage applied to the drive circuit, i.e., the drive voltage, falls on the series connection between the first circuit section and the other circuit section.

[0064] Figure 3 A schematic circuit diagram of an antenna device 1 according to a second embodiment of the present invention is shown. Figure 2 Compared to the implementation scheme shown, Figure 3 The antenna device 1 shown includes an additional compensation capacitor element CC1, specifically a compensation capacitor. The compensation capacitor element CC1 is electrically disposed in a first circuit section, wherein the first circuit section includes a series connection of the first compensation capacitor element CC1 and the first inductive antenna element L1.

[0065] Figure 4 A schematic circuit diagram of an antenna device 1 according to a third embodiment of the present invention is shown. Figure 3 Compared to the illustrated embodiment, antenna device 1 includes a second additional compensation capacitor element CC2, specifically a compensation capacitor. In this case, the second compensation capacitor element CC2 is electrically disposed in another sub-section of another circuit section, which may include a second inductive antenna element L2, the second additional compensation capacitor element CC2, and a resistor element R connected in series.

[0066] Figure 5 A schematic circuit diagram of an antenna device 1 according to a fourth embodiment of the present invention is shown. Figure 2 Compared to the previous implementation, the circuit arrangement does not include the additional resistive element R. In particular, the resistance of another sub-section of another circuit section is provided by the internal or implicit resistance of the second inductive antenna element L2.

[0067] and Figure 2In a further comparison of the illustrated embodiments, antenna device 1 includes a first compensating inductor element CCL1 and a second compensating inductor element CCL2. The first compensating inductor element CCL1 is arranged in a first circuit section and connected in series with the first inductor antenna element L1. The second compensating inductor element CCL2 is arranged in another subsection of another circuit section and connected in series with the second inductor antenna element L2.

[0068] Figure 5 The points shown indicate that the two compensating inductors CCL1 and CCL2 are configured and / or arranged such that the voltage induced in the first compensating inductor CCL1 by an external electromagnetic field (particularly an electromagnetic field used for inducing power transmission) is reverse-oriented relative to the voltage induced in the second compensating inductor CCL2 by the same electromagnetic field, but has the same absolute value. Reverse orientation can specifically mean that the voltage induced in the first compensating inductor CCL1 is oriented from the terminal connected to the first circuit portion of the voltage source 3 towards the terminal connected to the first circuit portion of the other circuit portion, wherein the voltage induced in the second compensating inductor CCL2 is oriented from the terminal connected to the other circuit portion of the voltage source 3 towards the terminal connected to the other circuit portion of the first circuit portion.

[0069] exist Figure 2 , Figure 3 , Figure 4 and Figure 5 In the illustrated embodiment, the inductors CCL1, CCL2, L1, L2, the capacitors CC1, CC2, C, and the resistor R can be selected or chosen such that the absolute value of the reactance of the first circuit portion is equal to the reactance of the first sub-circuit of the other circuit portion and equal to the reactance of the other sub-part of the other circuit portion.

[0070] Furthermore, these components can be selected such that the resonant frequency of the drive circuit corresponds to a predetermined frequency of the drive voltage.

[0071] If voltage source 3 generates the driving voltage, the inductive antenna elements L1 and L2 will generate positioning signals provided by the electromagnetic positioning field. These positioning signals will cause the antenna device 1 shown in the figures to generate an elliptical, and particularly circular, two-dimensional electromagnetic field. Specifically, Figure 2 , Figure 3 , Figure 4 and Figure 5 The antenna device 1 proposed herein, as shown, will provide current within the inductive antenna elements L1 and L2, wherein the current flowing through the first inductive element L1 has a 90° phase shift and flows to the second inductive antenna element L2.

[0072] The positioning signals generated by the inductive antenna elements L1 and L2 can be received by a receiving antenna device, which may include at least one, preferably two or more, receiving antenna elements. The receiving antenna device may also include an evaluation unit, particularly provided by or including a microcontroller, which allows determination of the relative position and / or orientation between the antenna device 1 used to generate the positioning signal and the receiving antenna device. Specifically, if a positioning signal is received, the evaluation unit can determine the signal characteristics of the voltage induced in the receiving antenna device.

[0073] For example, a receiving antenna device with the same circuit arrangement as the antenna device 1 proposed herein for generating positioning signals can be provided.

[0074] Figure 6 A schematic block diagram of an antenna device 1 and a receiving antenna device 4 according to the present invention is shown. The diagram further shows a coordinate system CS1, which includes a vertical axis x1 and a vertical axis z1, and another horizontal axis (not shown) fixed relative to the antenna device 1 in position and / or direction. The diagram further shows another coordinate system CS4, which includes a vertical axis x4 and a vertical axis z4, and a horizontal axis (not shown) fixed relative to the receiving antenna device 4 in position and / or direction. The relative position and / or orientation between the antenna device 1 and the receiving antenna device 4 may correspond to the relative position and / or orientation between coordinate systems CS1 and CS4. The relative position and / or orientation may also be determined in one of these coordinate systems CS1 and CS4.

[0075] The accompanying drawings further illustrate that the antenna device 1 for generating a positioning signal can be part of unit 5, particularly a primary or secondary unit of a system for inductive power transmission. This unit may include a winding structure for generating or receiving an electromagnetic field for inductive power transmission. Furthermore, unit 5 can be mounted, for example, above or below a vehicle path. Alternatively, unit 5 can be arranged at or within a vehicle, particularly on the underside of the vehicle. The accompanying drawings further illustrate that the receiving antenna device 4 can also be part of unit 6, particularly another part of a system for inductive power transmission, particularly a secondary or primary unit.

Claims

1. A positioning signal generating antenna device for use with a receiving antenna device and with an evaluation unit in operative communication with the receiving antenna device, wherein the evaluation unit determines a relative position between the positioning signal generating antenna device and the receiving antenna device based on a positioning signal generated by the positioning signal generating antenna device in use, the positioning signal having a position determining property which the evaluation unit uses to determine the relative position; wherein the positioning signal generating antenna device comprises a voltage source, a first inductive antenna element, a second inductive antenna element and at least one capacitive element, wherein the voltage source is electrically connected in parallel to a series connection of a first circuit portion comprising at least the first inductive antenna element and a further circuit portion comprising: a parallel connection of a first sub-portion of the further circuit portion comprising the at least one capacitive element and a further sub-portion of the further circuit portion comprising at least the second inductive antenna element, wherein the first inductive antenna element and the second inductive antenna element are configured and arranged to generate respective positioning signals having the position determining property when an alternating voltage having predetermined properties provided by the voltage source is applied; and during operation of the positioning signal generating antenna device, the positioning signal generating antenna device generates a circular electromagnetic field or an elliptical electromagnetic field.

2. The positioning signal generating antenna device according to claim 1, characterized in that the reactance of the first circuit portion is equal to the reactance of the first sub-portion of the further circuit portion and / or equal to the reactance of the further sub-portion of the further circuit portion.

3. The positioning signal generating antenna device according to claim 1, characterized in that The positioning signal generating antenna device comprises at least one resistive element, wherein the further sub-portion comprises a series connection of at least the second inductive antenna element and the at least one resistive element.

4. The positioning signal generating antenna device according to claim 1, characterized in that The positioning signal generating antenna device comprises at least one additional compensating capacitive element.

5. The positioning signal generating antenna device according to claim 4, characterized in that The first circuit portion comprises a series connection of a compensating capacitive element and the first inductive antenna element and / or the further sub-portion comprises a series connection of a compensating capacitive element and the second inductive antenna element.

6. The positioning signal generating antenna device according to claim 1, characterized in that The positioning signal generating antenna device comprises at least one additional compensating inductive element.

7. The positioning signal generating antenna device according to claim 6, characterized in that The first circuit portion comprises a series connection of a compensating inductive element and the first inductive antenna element and / or the further sub-portion comprises a series connection of a compensating inductive element and the second inductive antenna element.

8. The positioning signal generating antenna device according to claim 6, characterized in that The positioning signal generating antenna device comprises at least two compensating inductive elements, wherein the at least two compensating inductive elements are provided by a coil, wherein the coil is wound in opposite directions.

9. The positioning signal generating antenna device according to claim 1, characterized in that The positioning signal generating antenna device comprises at least one magnetic conductive element, wherein at least one inductive antenna element is wound around at least a portion of the magnetic conductive element.

10. The positioning signal generating antenna device according to claim 9, characterized in that The first inductive antenna element and the second inductive antenna element are wound around different portions of the magnetic conductive element; or The positioning signal generating antenna device comprises a first magnetic conductive element and a further magnetic conductive element, wherein the first inductive antenna element is wound around the first magnetic conductive element and the second inductive antenna element is wound around the further magnetic conductive element.

11. The positioning signal generating antenna device according to claim 9, characterized in that The magnetic conductive element is a magnetic conductive element of a secondary unit of a system for inductive power transfer.

12. The positioning signal generating antenna device according to claim 1, characterized in that A central axis of the first inductive antenna element is not oriented in parallel to a central axis of the second inductive antenna element.

13. The positioning signal generating antenna device according to claim 1, characterized in that, During operation of the positioning signal generating antenna device, the voltage source generates an alternating voltage.

14. The positioning signal generating antenna device according to claim 13, characterized in that The frequency of the alternating voltage equals a resonance frequency of the series connection of the first circuit portion and the further circuit portion.

15. The positioning signal generating antenna device according to claim 1, characterized in that, During operation of the positioning signal generating antenna device, the positioning signal generating antenna device generates a positioning signal by causing a predetermined phase difference between a current flowing through the first inductive antenna element and a current flowing through the second inductive antenna element.

16. An antenna device comprising: a voltage source; a first inductive antenna element; a second inductive antenna element; and at least one capacitive element; wherein: the voltage source is electrically connected in parallel to a series connection of a first circuit portion and a further circuit portion, the first circuit portion comprising at least the first inductive antenna element, the further circuit portion comprising a parallel connection of a first sub-portion of the further circuit portion comprising the at least one capacitive element and a further sub-portion of the further circuit portion comprising at least the second inductive antenna element; the first inductive antenna element and the second inductive antenna element are configured and arranged to generate a positioning signal; and during operation of the antenna device, the antenna device generates a circular electromagnetic field or an elliptical electromagnetic field.

17. A method of operating a positioning signal generating antenna device according to any one of claims 1 to 15 or an antenna device according to claim 16, characterized by, An alternating voltage is generated by the voltage source.

18. The method of claim 17, wherein, The frequency of the generated voltage equals a resonance frequency of the series connection of the first circuit portion and the further circuit portion.

19. A system comprising the positioning signal generating antenna device of claim 1 and an evaluation unit.

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