Method and device for determining a relative position of a primary and secondary side of a contactless energy transmission system

Abstract

The present invention relates to a method and a device for determining a relative position of a primary side (10) and a secondary side (20) of a contactless energy transmission system (100). The method comprises the steps of: a) exciting the primary side (10) and / or the secondary side (20) of the energy transmission system (100) in order to generate a response signal (F1) of the primary side (10) and / or the secondary side (20) of the energy transmission system (100) dependent on the relative position to be determined; b) detecting the response signal (F1); and c) determining the relative position on the basis of the detected response signal (F1). The invention further relates to a use of the method according to the invention and of the device according to the invention.

Description

[0001] Applicant: University of Stuttgart

[0002] "Method and device for determining a relative position of a primary and secondary side of a contactless energy transmission system"

[0003] Our reference: S16247WO - hy / msc

[0004] Description

[0005] The invention relates to a method and a device for determining a relative position of a primary and secondary side of a contactless energy transmission system.

[0006] In wireless energy transfer or charging systems, such as those increasingly used for charging electric vehicles, precise alignment of the primary and secondary sides of the energy transfer system is crucial. The transmission efficiency and operational reliability depend significantly on the geometric arrangement of the primary and secondary sides of the contactless energy transfer system. For example, in inductive energy transfer or charging systems, the geometric arrangement of the transmission coils (i.e. the primary or transmitting coil and the secondary or receiving coil) is particularly important, since only the portion of the magnetic flux that creates intertwined flux lines in the area of ​​the respective coil can be used for energy transfer. In particular, the magnetic coupling between the transmission coils of an inductive energy transfer system depends significantly on their geometric arrangement.Since the proportion of the magnetic flux that can be used for energy transmission is determined by the spatial extent of the alternating magnetic field, knowledge of the relative positioning between the transmitter (primary side) and receiver (secondary side) plays a central role in the operation of the charging system. The challenge of sufficiently precise alignment of the transmission coils is particularly evident in charging systems with transmission power > 1 kW, as is the case in automotive applications, for example. In order to comply with the permissible operating limits, a minimum accuracy in the positioning of the transmission coils is required. The established solution for position determination to date has been assistance systems that use separate sensors in addition to the energy transmission system and are physically based on an electromagnetic near and / or far field. For this purpose, additional components must be installed in the charging units.For near-field solutions, for example, additional signal coils are used, which are usually operated in a different frequency range than the energy transmission coils with significantly lower power. These near-field solutions therefore require, in addition to the dedicated signal coils (separate transmitting and receiving units), corresponding signal and power electronics for signal generation and signal evaluation. Far-field solutions are essentially based on a time-of-flight measurement of electromagnetic waves, in which signal propagation times and the triangulation principle are used for localization. These far-field solutions use, for example, UWB (ultra-wideband) for position determination using a time-of-flight measurement. In environments with many network participants, such asIn public parking areas during stationary charging or on long (and / or multi-lane) electrified road sections during dynamic charging, there are hard real-time requirements that can no longer be guaranteed once a critical number of network participants are reached.

[0007] The additional hardware of conventional positioning systems increases product costs and also increases the risk of failure. Conventional solutions require the charging units to be equipped with appropriate hardware on both sides, which must be continuously supplied with power during operation ("standby" supply, during which no vehicle is parking or charging). Both transmitters and receivers of conventional positioning systems therefore require a continuous power supply. In particular, an electromagnetic near- or far-field must be generated continuously (or pulsed or averaged over time). In previous positioning solutions, both the secondary and primary sides must follow a fixed pattern to achieve interoperability. Optical systems or cameras are considered to be unreliable under environmental influences such as snow, autumn leaves, pollution, etc., as unsuitable for positioning the primary and secondary sides of a contactless energy transmission system. Therefore, it is an object of the present invention to improve the determination of the relative position of the primary and secondary sides of a contactless energy transmission system, particularly with regard to space requirements, simplicity, reliability, and / or cost. This object is achieved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0008] A first independent aspect for solving the problem relates to a method for determining a relative position of a primary and secondary side of a contactless energy transmission system, comprising the steps: a) exciting the primary and / or secondary side of the energy transmission system to generate a response signal of the primary side and / or the secondary side of the energy transmission system that is dependent on the relative position to be determined; b) detecting (in particular measuring) the response signal; and c) determining the relative position based on the detected (in particular measured) response signal.

[0009] The contactless or wireless energy transmission system can, for example, be an inductive or capacitive energy transmission system. In particular, the energy transmission system is a system for transmitting electrical energy, in particular from the primary side to the secondary side, or for converting electrical energy (on the primary side) into electrical energy (on the secondary side). The wireless energy transmission system is preferably a system for capacitive or inductive charging. "Determining a relative position of a primary and secondary side" is thus understood to mean, in particular, determining the relative position of at least one primary electrode (or a pair of primary electrodes) and at least one secondary electrode (or a pair of secondary electrodes), or determining the relative position of at least one primary winding (or primary coil) and at least one secondary winding (secondary coil).The primary side (also referred to as the transmitter unit in this description) comprises in particular one or more primary electrodes or primary electrode pairs or one or more primary windings or primary coils. Correspondingly, the secondary side (also referred to as the receiver unit in this description) comprises in particular one or more secondary electrodes or secondary electrode pairs, or one or more secondary windings or secondary coils. A relative position of a primary and secondary side is therefore understood to mean in particular a relative position of a primary and secondary electrode (or a primary and secondary electrode pair), or a relative position of a primary and secondary winding (or primary and secondary coil). It is understood that the primary side or secondary side can also each comprise further elements, such as a power inverter, a compensation circuit ora compensation network and / or signal electronics.

[0010] The relative position of the primary and secondary sides comprises, in particular, position data or coordinates relating to the relative position of the primary and secondary sides, in particular the relative position of a primary and secondary electrode or the relative position of a primary and secondary winding. For example, the relative position (or the position data) can comprise a distance between the primary and secondary sides. In particular, the relative position comprises or is a position (specified, for example, in coordinates) of the secondary side (e.g., a secondary electrode or a secondary winding) of the energy transmission system relative to the primary side (e.g., a primary electrode or a primary winding) of the energy transmission system, and / or a position (specified, for example, in coordinates) of the primary side (e.g., a primary electrode or a primary winding) of the energy transmission system relative to the secondary side (e.g.,a secondary electrode or a secondary winding) of the energy transmission system. For example, the relative position (or the position data) can include or be a relative position of a vehicle (in particular a transmission winding of the vehicle) to a charging point and / or a charging section (or a transmission winding of the charging point and / or the charging section). The excitation of the energy transmission system or its primary and / or secondary side takes place in particular with the aid of an (e.g. electrical) excitation signal, which can be a voltage and / or current signal, for example. In particular, the excitation signal is designed to generate or cause a response signal of the energy transmission system, in particular a response signal of the primary side of the energy transmission system and / or a response signal of the secondary side of the energy transmission system.The response signal induced by the excitation can be a transient or steady-state response signal (representing a corresponding transient or steady-state response of the energy transfer system). For example, the excitation signal can represent a disturbance signal that (at least briefly or temporarily) disrupts or destabilizes an energetic state of the energy transfer system. In other words, the excitation signal can destabilize the energy transfer system (at least briefly or temporarily), to which the energy transfer system reacts, for example, with a transient system response (system response), e.g., in the form of specific current and / or voltage waveforms on the primary and / or secondary side of the energy transfer system.

[0011] The detection of the response signal comprises or is carried out, in particular, by measuring the response signal. In particular, the detection of the response signal comprises a current and / or voltage measurement. The response signal depends on the relative position of the primary and secondary sides of the energy transmission system and can thus serve as a basis for determining the relative position of the primary and secondary sides of the energy transmission system.

[0012] From a physical perspective, the inherent position dependence of resonance points in the energy transfer system is exploited to infer the relative positioning of the primary and secondary sides (in particular, relative coil positioning) based on observed system behavior. In the case of an inductive energy transfer system with transmission coils, such position-dependent system behavior is caused in particular by the magnetic flux guidance and / or flux displacement of materials in the immediate vicinity of the transmission coils.

[0013] The position-dependent system behavior of the energy transfer system (e.g., a charging system) can thus be directly observed, and the relative positioning of the primary and secondary sides can be estimated. This allows the position determination function to be integrated into existing energy transfer hardware in a simple, cost-effective, and reliable manner.

[0014] The invention enables improved determination of the relative position of the primary and secondary sides of a contactless energy transmission system, particularly with regard to space requirements, simplicity, reliability, and / or cost. With the aid of the present invention, it is particularly possible to determine the relative positioning of the primary and secondary sides (e.g., the transmission coils) without the use of sensors, i.e., without the use of additional sensors, but rather solely using the sensors already present in the surrounding system.

[0015] The present invention thus provides, in particular, sensorless position determination between the primary and secondary sides of a contactless energy transmission system (e.g., between the transmission windings of an inductive energy transmission system). In this context, "sensorless" means, for example, that no additional or separate assistance system is required, as the inherent properties of the energy transmission system are utilized.

[0016] In particular, to determine the relative position of the primary and secondary sides of a contactless energy transfer system, only the (already existing) transmission coils of the energy transfer system are used. Advantageously, no additional coils and / or a coil array are required for position determination. Instead, inherent or already existing signals of the power circuit or energy transfer system are used to determine the relative position of the primary and secondary sides. In particular, excitation signals and their respective reactions or responses are used to determine the relative position without additional sensors. Preferably, a temporally repeating sequence of excitation signals (and their respective reactions or responses) is generated while the magnetically coupled coils of the primary and secondary sides move relative to one another. An evaluation of the responses orResponse signals advantageously allow a conclusion to be drawn about the (current) relative position of the coils. The relative position of the primary and secondary sides of the energy transmission system can advantageously be determined with just a single primary or transmitting coil and / or with just a single secondary or receiving coil. In particular, a change in the response to an excitation signal that occurs during a relative movement between the primary side and secondary side (in particular between the transmitting and receiving coil) of the energy transmission system or that results from a relative movement between the primary side and secondary side is exploited. For this reason, a single primary or transmitting coil is sufficient to determine the relative position of the primary side and the secondary side. In particular, the position can be determined by multiple excitation with an excitation signal and the evaluation of several associated reactions orResponses of the inductive energy transfer system occur. In particular, the position determination is based on a change in the relative position between the primary side (or primary coil) and the secondary side (or secondary coil).

[0017] The method and device described herein are particularly characterized by the fact that no additional sensors are required to determine the relative position of the primary and secondary sides of an energy transmission system. This is accompanied by a minimized hardware dependency. In particular, the method described herein for determining a relative position of a primary side and secondary side of a contactless energy transmission system is carried out exclusively by evaluating system-specific signals within the energy transmission system or an energy transmission circuit of the energy transmission system. The use of existing structures and components of the energy transmission enables an energy-efficient design and significantly simplifies the construction of a corresponding device. The method and device according to the invention can be used both for stationary inductive charging (e.g.It can be used both in parking an electric vehicle and in dynamic inductive energy transfer (e.g., as a lane-keeping assistance system). In particular, knowledge of the geometric arrangement of the primary and secondary sides can be used, for example, in stationary contactless charging systems (especially for implementing a parking assistant) and / or in dynamic contactless charging (especially for implementing a lane-keeping assistant).

[0018] In a preferred embodiment, one or more of steps a) to c) are performed during a relative movement of the primary side and the secondary side. In particular, all of steps a) to c) are performed during a relative movement of the primary side and the secondary side. In other words, preferably at least one of steps a) to c), or all of steps a) to c), are performed while the primary side and the secondary side are moving relative to one another.

[0019] In a further preferred embodiment, the above-mentioned steps a) to c), which represent a position estimation, are repeated cyclically. For example, this cyclical repetition can be carried out until a stop instruction is given or until a predetermined relative position is reached. In this case, knowledge of one or more previous position estimations, in particular those carried out by means of steps a) to c), is preferably taken into account in the position determination of the respective current position. In other words, a position estimation routine is preferably carried out which comprises a plurality of cyclically repeated position estimations, in particular by means of steps a) to c). Furthermore, preferably, in particular during the execution of the position estimation routine, a movement trajectory of the secondary side is detected and, in particular based on driving data (such as steering angle and / or wheel speed, etc.), and / or based on vehicle data (such as wheelbase and / or wheel circumference, etc.). Such an evaluation can advantageously serve to improve position estimation.

[0020] In a further preferred embodiment, a position estimation routine is carried out which comprises a plurality of cyclically repeating position estimations by means of steps a) to c).

[0021] In a further preferred embodiment, the position estimation routine is performed during a relative movement of the primary side and the secondary side of the contactless energy transfer system. In particular, the primary side and the secondary side move relative to each other while the position estimation routine is performed.

[0022] In a further preferred embodiment, a movement trajectory of the secondary side is detected, in particular during the execution of the position estimation routine.

[0023] In a further preferred embodiment, the primary side comprises only a single primary coil or transmitting coil. In particular, the relative position of the primary side and the secondary side is determined based on only a single primary coil or transmitting coil, namely in particular exclusively based on the (single) primary coil or transmitting coil of the energy transmission system. Preferably, the secondary side comprises only a single secondary coil or receiving coil. In particular, the relative position of the primary side and the secondary side is determined based on only a single secondary coil or receiving coil, namely in particular exclusively based on the (single) secondary coil or receiving coil of the energy transmission system.

[0024] In a further preferred embodiment, the response signal is acquired by a voltage and / or current measurement on the primary side and / or the secondary side of the energy transmission system. The sampling of current and voltage signals (in the time domain) is preferably performed using an analog-to-digital converter (ADC), i.e., a digital or digitized response signal is generated from the acquired (analog) response signal using an analog-to-digital converter. The sampling frequency is preferably in the range of several hundred kHz to several MHz.The sampling frequency is selected in particular such that at least one highest occurring natural frequency of the energy transmission system (according to the Nyquist-Shannon criterion) is present in the digitized response signal, and / or that preferably the digitized response signal generated by means of the ADC accurately maps the amplitudes and phase positions of the detected (analog) response signal within a predetermined frequency spectrum (in particular from zero to the highest occurring natural frequency of the energy transmission system).

[0025] In a further preferred embodiment, the response signal reflects a transient transient response and / or a steady-state frequency response of the primary and / or secondary side of the energy transmission system. In other words, the response signal represents a transient transient response and / or a steady-state frequency response of the primary and / or secondary side of the energy transmission system.

[0026] In a further preferred embodiment, the response signal is based on a transient system response of the energy transmission system, wherein the relative position is determined based on a determination of frequency components of the transient system response. Alternatively or additionally, the detected response signal is based on a stationary system response of the energy transmission system, wherein the relative position is determined based on a determination of an amplitude and / or a phase position and / or at least one pole and / or zero of the stationary system response.

[0027] In particular, the relative position between the primary and secondary sides of the energy transfer system (e.g. between the transmission coils of an inductive energy transfer system) can be determined from the response signal using one or more of the following information: - Frequency components of a transient system response (in particular frequency, amplitude, phase position and / or attenuation of frequency components present in the response signal);

[0028] - Amplitude of a stationary system response (in particular an amplification of the response signal relative to the excitation or excitation signal);

[0029] - Phase position of the stationary system response (in particular a delay of the response signal relative to the excitation or excitation signal).

[0030] From such an analysis it is possible in particular to reconstruct the position of the poles and / or zeros and thus to determine one or more of the changing parameters L1, L2, M, k of a transfer function {Z1,Z2, ...} = f(Li,L2,M, k) zu identify. Here, Z denotes r an impedance of the primary side, Z2 an impedance of the secondary side, M a mutual inductance between the coupled transmission coils (ie the primary coil with an inductance and the secondary coil with an inductance L2) of the energy transmission system, and k is a coupling factor between the primary and secondary coils (or the primary and secondary sides). The parameters {L ltL2,M,k} = f(x,y,z') are in turn dependent on the spatial coordinates x, y, z, and thus allow conclusions to be drawn about the relative position of the transmission coils (or the primary and secondary sides). The impedances Z and Z2 are each dependent on the position of the primary and / or secondary side. In particular, the impedances Z x and Z2 depend on the relative positioning (or relative position) of the primary and secondary sides. Furthermore, the impedances Z and Z are frequency-dependent quantities. In the context of this description, a transfer function is understood in particular to be a function that describes a relationship between the excitation signal and the response signal of the energy transfer system.

[0031] In a further preferred embodiment, detecting the response signal comprises determining at least one transfer function of the energy transmission system (dependent on the relative position of the primary and secondary sides). The transfer function, in particular the above-mentioned transfer function {Z 1(Z2, ■■■} = f(Li>L2, M, k'), depends in particular on a position of the primary and / or secondary side. In particular, the transfer function depends on the relative positioning (or relative position) of the primary and secondary sides. In particular, the detection of the response signal comprises determining at least one impedance (dependent on the relative position of the primary and secondary sides) of the primary side and / or the secondary side of the energy transmission system. For this purpose, in particular, current and voltage are measured at a winding or coil of the primary side (primary winding or primary coil) and / or at a power inverter of the primary side, and / or current and voltage are measured at a winding or coil of the secondary side (secondary winding or secondary coil) and / or at a power rectifier of the secondary side.

[0032] In a further preferred embodiment, the relative position is determined based on a determination of poles and / or zeros of the at least one transfer function (or of the at least one impedance). In particular, a pole-zero diagram and / or a Bode diagram of the at least one transfer function is used to determine the relative position. Alternatively or additionally, a shift of the poles and / or zeros of the at least one transfer function can also be used to determine the relative position. The shift of the poles and / or zeros of, for example, the impedance Z x = on the primary side or the impedance Z2 = U2 / on the secondary side results in the gain and / or delay of the input or excitation signal changing during the alignment of the primary and / or secondary side (especially during electrode or coil alignment). In other words, the Bode diagram of the transfer function changes. For this reason, a continuous PWM signal (PWM = "pulse width modulation") can also be used to excite the primary and / or secondary side of the energy transfer system, and thus for position determination. This approach is not based on the analysis of a transient transient response, but on the observation of a steady-state frequency response of the energy transfer system. In other words, an excitation with a PWM signal (a fundamental wave frequency f0) experiences a position-dependent gain and / or delay of the excitation signal according to the position-dependent Bode diagram.Such position-dependent amplification and / or delay can be determined from the detected response signal. In the event that the excitation and evaluation (i.e., the detection of the response signal) take place on separate sides (excitation on the primary side and response on the secondary side, or excitation on the secondary side and response on the primary side), current and / or voltage transfer functions, e.g., of the form , can be used alternatively or additionally (depending on the topology of a charging system) for parameter identification. and thus to determine the relative position of the primary and secondary sides. U- denotes a voltage on the primary side, U2 a voltage on the secondary side, a current on the primary side, I2a current on the secondary side, L the inductance of a primary coil, L2the inductance of a secondary coil and M the mutual inductance between primary and secondary coil

[0033] In a further preferred embodiment, determining the relative position comprises determining one or more of the following parameters:

[0034] - Inductance L of a primary winding of the energy transmission system (or the primary side of the energy transmission system),

[0035] - Inductance L2 of a secondary winding of the energy transmission system (or the secondary side of the energy transmission system),

[0036] - Mutual inductance M of the primary winding and secondary winding,

[0037] - Coupling factor k of the primary winding and secondary winding.

[0038] Alternatively or additionally, determining the relative position may comprise determining quantities that are physically directly related to the above-mentioned parameters or can be converted into related quantities, such as one or more magnetic fluxes, one or more induced voltages, and / or one or more induced currents.

[0039] In other words, to determine the relative position of the primary and secondary sides of the contactless energy transmission system, parameter identification is carried out, wherein the parameters are in particular one or more parameters of a transfer function (of the energy transmission system). In a further preferred embodiment, the relative position of the primary and secondary sides is determined with the aid of at least one predetermined characteristic map. The one or more characteristic maps can, for example, comprise a location-dependent coupling profile and / or a profile of inductances. Alternatively or additionally, the relative position of the primary and secondary sides is determined with the aid of a Kl algorithm (Kl = “artificial intelligence”), in particular with the aid of a neural network and / or a machine learning algorithm. In particular, the implementation of a Kl algorithm for a dynamic analysis of the response signal orthe system response can significantly improve the efficiency and flexibility of the process.

[0040] For parameter identification, a Kalman filter and / or observer can be used. This is particularly advantageous when the number of different coil pairs is small (e.g., in an industrial application, there are usually only a few different coil types or manufacturers). In such a case, the position-dependent system behavior can already be adequately represented by one or more characteristic maps and / or look-up tables. Using a Kalman filter, for example, one or more of the parameters L ltL2 and M of a transfer function are estimated. Using one or more predetermined characteristic maps, such as a characteristic map L1(x,y,z') relating to the inductance of a primary coil of the energy transmission system, a characteristic map L2(x,y,z) relating to the inductance of a secondary coil of the energy transmission system and / or a characteristic map M(x,y,z) relating to the mutual inductance between the primary and secondary coils of the energy transmission system, the relative position (x,y,(z)) of the primary and secondary sides of the energy transmission system can then be directly deduced. Since an air gap between the coils of an inductive energy transmission system is normally not changed, the z-coordinate does not necessarily have to be estimated.

[0041] In an open environment, such as the charging of electric vehicles, there is a wide range of vehicle types, manufacturers, and degrees of freedom regarding system design, so that the use of a class-A controller is particularly advantageous in such a case to accommodate the wide variety of variants. Despite the wide variety of variants, however, it has been shown within the scope of the present invention that, in principle, similar effects can be assumed during the alignment of the primary and secondary sides, particularly because charging systems in the automotive sector are subject to standardization to ensure interoperability.Since the electromagnetic behavior of the transmission coils of an inductive energy transmission system can be very well simulated, it is possible to train a Cl using an FEM simulation (FEM = "finite element method") with a large number of test systems, thus eliminating the need for complex prototype measurements of different variants. For example, it is possible to use model- or non-model-based Cl approaches that either estimate one or more of the parameters L via an intermediate step. 1( L2 and M (as with the Kalman filter), or use the system response or the recorded response signal to directly infer the relative position, in particular the position coordinates x, y, and optionally z.

[0042] In a further preferred embodiment, the method is a method for positioning a vehicle. To determine the relative position (of the primary and secondary sides of the contactless energy transfer system), driving data (such as a steering angle and / or a tire position and / or a wheel speed, etc.) read from the vehicle and / or vehicle data (such as a wheelbase and / or a wheel circumference, etc.) are preferably taken into account. In particular, such driving data and / or vehicle data can be incorporated into the training of a Kl algorithm. In this way, the accuracy of determining the relative position of the primary and secondary sides can be advantageously increased. In particular, knowledge of the temporal course of secondary side kinematics, e.g. in automotive applications, can be used in the form of driving data (such as steering angle, tire position, wheel speed, etc.) and / or vehicle data (such as wheelbase, wheel circumference, etc.).) can be used to restrict a solution space of possible relative positions and thus improve the accuracy of position estimation.

[0043] A further independent aspect for solving the problem relates to a computer program product comprising machine-readable program code which, when loaded onto a computer or processor, is suitable for executing the inventive method described above. In particular, the computer or processor can be designed (or programmed) (with the aid of the program code) to control one or more components of the energy transmission system, in particular one or more components of the primary and / or secondary circuit of the energy transmission system, in order to execute the inventive method. In particular, the computer or processor can be designed (or programmed) to control a voltage and / or current source of the energy transmission system (in particular on its primary and / or secondary side) in order to excite the primary and / or secondary side (with an excitation signal in the form of a voltage and / or current signal).Furthermore, the computer or processor can be designed (or programmed) to control a voltage and / or current measuring device of the energy transmission system (in particular on its primary and / or secondary side) in order to detect or measure a response signal of the primary and / or secondary side.

[0044] A computer program product can, for example, be a program stored on a data carrier. In particular, the program code is stored on the data carrier. In other words, the computer program product can comprise computer-readable instructions which, when loaded into a memory of a computer or processor and executed by the computer or processor, cause the computer or processor to carry out an inventive method described above. The invention thus provides, in particular, a computer program product, e.g. in the form of a storage medium or a data stream, which contains program code which, when loaded and executed on a computer or processor, is designed to carry out a method for determining a relative position of a primary and secondary side of a contactless energy transmission system according to the present invention, in particular in a preferred embodiment.

[0045] A further independent aspect for solving the problem relates to a device for determining a relative position of a primary side and a secondary side of a contactless energy transmission system, comprising: an excitation unit for exciting the primary and / or secondary side of the energy transmission system and for generating a response signal of the primary side and / or the secondary side of the energy transmission system that is dependent on the relative position to be determined; a detection unit (in particular a measuring unit) for detecting (in particular measuring) the response signal; and an evaluation unit for determining the relative position based on the detected (in particular measured) response signal.

[0046] The excitation unit, the detection unit and / or the evaluation unit are preferably controlled by at least one processor or microprocessor, which can be integrated, for example, into at least one signal electronics or signal electronics unit of the energy transmission system or the primary and / or secondary side of the energy transmission system or into which at least one signal electronics unit is integrated.

[0047] In a preferred embodiment, the device described above for determining a relative position of a primary side and a secondary side of a contactless energy transmission system is a component of the energy transmission system or a component of the primary and / or secondary side of the energy transmission system.

[0048] In a further preferred embodiment, the device is designed to carry out, in particular by means of a processor, a position estimation routine which comprises a plurality of cyclically repeating position estimates by means of the excitation unit, the detection unit and the evaluation unit. In particular, the device comprises a processor which is designed to control the excitation unit, the detection unit and the evaluation unit in order to carry out, in particular during a relative movement of the primary side and the secondary side of the contactless energy transmission system, a position estimation routine which in particular comprises a plurality of cyclically repeating position estimates. Preferably, the device (orIn particular, the processor and / or the excitation unit, the detection unit, and the evaluation unit are designed to detect a movement trajectory of the secondary side, in particular during the execution of the position estimation routine and / or during a relative movement of the primary side and the secondary side of the contactless energy transfer system. In particular, the movement trajectory (of the secondary side) comprises position data that indicates or represents a relative movement of the primary side and the secondary side (e.g., a movement of the secondary side relative to the primary side and / or a movement of the primary side relative to the secondary side).

[0049] A further independent aspect for solving the problem relates to a transmitter unit (or a primary side) and / or a receiver unit (or a secondary side) of a contactless (in particular capacitive or inductive) energy transmission system, which comprises / comprise the above-mentioned device according to the invention. In particular, the invention therefore relates to a contactless (in particular capacitive or inductive) energy transmission system (primary and secondary side) which comprises the above-mentioned device according to the invention. The energy transmission system can, for example, be a contactless (in particular capacitive or inductive) charging system for electric vehicles. In this case, inductive energy transmission is based in particular on an alternating magnetic field, preferably between two windings or coils (which are referred to as primary and secondary windings or primary and secondary coils).Capacitive energy transfer is based in particular on an electric field, preferably between two pairs of electrodes (which are referred to as primary and secondary electrode pairs).

[0050] A further independent aspect for solving the problem relates to a use of the method according to the invention or the computer program product according to the invention for (assisted) parking of a vehicle and / or for (assisted) lane keeping of the vehicle. For example, the method according to the invention or the computer program product according to the invention can be used in a vehicle, in particular in an electric vehicle with a contactless (inductive or capacitive) charging device. A further independent aspect for solving the problem relates to a use of the device according to the invention or the receiver unit according to the invention of a contactless energy transmission system (in particular of a contactless energy transmission system according to the invention) in a vehicle, in particular in an electric vehicle (in conjunction with a contactless or inductive or capacitive charging device), as a parking assistant and / or as a lane keeping assistant.

[0051] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in isolation or in other combinations without departing from the scope of the present invention.

[0052] The above-mentioned further independent aspects and in particular the related preferred embodiments are also subject to the above-mentioned or below statements regarding the embodiments of the first aspect. In particular, the above-mentioned and below statements regarding the embodiments of the respective other independent aspects also apply to an independent aspect of the present invention and the related preferred embodiments.

[0053] In the following, individual embodiments for achieving the object are described by way of example with reference to the figures. In some cases, the individual embodiments described have features that are not absolutely necessary to carry out the claimed subject matter, but which provide desired properties in certain applications. Thus, embodiments that do not have all the features of the embodiments described below are to be regarded as falling within the scope of the described technical teaching. Furthermore, to avoid unnecessary repetition, certain features are only mentioned in relation to individual embodiments described below. It is pointed out that the individual embodiments should therefore not only be considered in isolation, but also in conjunction with one another.Based on this overview, those skilled in the art will recognize that individual embodiments may also be modified by incorporating one or more features of other embodiments. It is noted that a systematic combination of the individual embodiments with one or more features described with reference to other embodiments may be desirable and useful and should therefore be considered and considered to be encompassed by the description.

[0054] Short description of the drawings

[0055] Figure 1 shows a schematic drawing of the magnetic coupling between two transmission coils 15 and 25 of an inductive energy transmission system 100;

[0056] Figure 2 shows a schematic drawing of an exemplary inductive energy transmission system 100 for explaining a method and apparatus according to a preferred embodiment of the invention;

[0057] Figure 3a shows an exemplary continuous excitation using an excitation signal in the form of a block pulse width modulation;

[0058] Figure 3b shows an exemplary continuous excitation using an excitation signal in the form of a pulse width modulation with a duty cycle < 50%;

[0059] Figure 3c shows an exemplary excitation using an excitation signal in the form of pulses or section-wise step functions;

[0060] Figure 3d shows an exemplary excitation using an excitation signal in the form of a discrete chirp signal;

[0061] Figure 3e shows an example of excitation using an excitation signal in the form of a delta-sigma modulated sine function; Figure 4a shows an example of a transient response of a secondary current I2(t) after a step-like PWM excitation on the primary side from the idle state;

[0062] Figure 4b shows an exemplary transient response of a primary current ZiC after a step-like PWM excitation on the primary side from the idle state;

[0063] Figure 5a shows a pole-zero diagram of a higher-order inductive charging system, with the secondary coil moving along a straight line across the center of the primary coil. The dashed trace of the poles and zeros in the positive imaginary half-plane indicates the path of displacement as the two coils move relative to each other;

[0064] Figure 5b shows a pole-zero diagram of a higher-order inductive charging system, where the secondary side is moved along a straight line offset by 200 mm. The poles and zeros have a different track during this displacement than for the displacement shown in Figure 5a.

[0065] Figure 6 shows a schematic flow diagram for explaining a method according to a preferred embodiment of the invention.

[0066] Detailed description of the drawings

[0067] Figure 1 shows a schematic drawing of the magnetic coupling between a primary winding or primary coil 15 and a secondary winding or secondary coil 25 of a contactless or inductive energy transmission system 100. For the sake of simplicity, only the transmission windings 15 and 25 are shown in Figure 1. Other components of the energy transmission system 100 are not shown in this figure. The mutual magnetic influence of the primary coil 15 and secondary coil 25 is described by the mutual inductance M, which is a function 7(θ) of the magnetic flux. As can be seen from Figure 1, the center of the secondary coil 25 is shifted relative to the center of the primary coil 15 (with the coordinates x0, y0, z0) by Ax in the x-direction, Ay in the y-direction, and Az in the z-direction. Due to this shift, only a portion of the magnetic flux 0, namely the so-called main flux 0, contributes h, contributes to the energy transfer from the primary coil 15 (primary side) to the secondary coil 25 (secondary side). Another part of the magnetic flux 0, namely the so-called stray flux <p a , however, cannot be used for energy transmission. Since the portion of the magnetic flux 0 usable for energy transmission depends on the relative position of the primary side (or primary coil 15) and secondary side (or secondary coil 25), knowledge of the relative positioning between the transmitter (primary coil 15) and the receiver (secondary coil 25) plays a central role in the operation of an inductive charging system. The present invention specifically addresses the challenge of determining the position between transmitting and receiving coils in systems for inductive energy transmission.

[0068] Figure 2 shows a schematic drawing of an exemplary inductive energy transmission system 100 for explaining a method and a device according to a preferred embodiment of the invention. The inductive energy transmission system 100 comprises two transmission windings 15 and 25, wherein one of these transmission windings, namely the primary winding 15, is assigned to a primary side 10 of the energy transmission system 100, and the other of the two transmission windings, namely the secondary winding 25, is assigned to a secondary side 10 of the energy transmission system 100. Electrical energy is transferred contactlessly or inductively from the primary side 10 of the energy transmission system 100 to the secondary side 20 of the energy transmission system 100. In addition to the transmission windings, other components of the energy transmission system 100 are also schematically illustrated in Figure 2.Thus, the primary side 10 includes the primary coil 15, which is an inductance. also comprises a power inverter A1, a compensation circuit or compensation network B1, and signal electronics D1. Accordingly, the secondary side 20 comprises, in addition to the secondary coil 25, which has an inductance L2, also a power rectifier A2, a compensation circuit or compensation network B2, and signal electronics D2.

[0069] With the help of an excitation signal E1, which is schematically indicated in Figure 2 and which in the example shown is applied as a voltage signal to the power inverter A1 on the primary side 10, a system response or a response signal F1 is elicited, which is evaluated via an evaluation unit or the signal electronics D1 and used for parameter identification in order to determine the relative position between the primary coil 15 and the secondary coil 25. In other words, a system response (e.g. in the form of current and / or voltage curves) as a result of a (short-term) disturbance in the energetic state of the energy transmission system 100 is used to infer the relative position of the transmission coils 15 and 25 through parameter identification. In particular, the inherent resonance characteristic of the energy transmission system 100 itself is used to determine the position or to determine the relative position of the transmission coils 15 and 25.This is possible because the resonance characteristics of the energy transmission system 100 depend on the relative position of the transmission coils 15 and 25. By specifically exciting a (e.g., transient) system response, in particular by exciting it with a voltage and / or current jump, the position-dependent system behavior can be observed. Relevant system parameters can be identified from the signal waveforms, and the identified system parameters can be used to determine the relative position of the transmission coils 15 and 25.

[0070] It is noted that the voltages and currents plotted in Figure 2 represent complex quantities and are therefore underlined. However, the underlining of these quantities is omitted for simplicity in the following. As indicated in Figure 2, for example, to detect a response of the primary side, a voltage and / or a current at the output of the inverter A1 , and / or a voltage U L1 and a current I L1 at the primary coil 15. Here, I denotes a current between an output of the power inverter A1 (or an input of the compensation circuit B1 ) and the signal electronics D1. The quantity I L1 denotes a current between the signal electronics D1 and an output of the compensation circuit B1 . Alternatively or additionally, corresponding quantities can be measured on the secondary side. For example, to detect a response from the secondary side, a voltage U2 and / or a current I2 at the input of the rectifier A2, and / or a voltage U L2 and a current I L2 measured at the secondary coil 25. I2 represents a current between an input of the power rectifier A2 (or an output of the compensation circuit B2) and the signal electronics D2. The quantity I L2denotes a current between the signal electronics D2 and an input of the compensation circuit B2. The index "ZK" used in Figure 2 stands for intermediate circuit, i.e., in particular, for a DC input voltage U ZK 1 at inverter A1 or for a DC output voltage U ZK>2 after the rectifier A2. U ZK ^ is therefore also called intermediate circuit voltage on the primary side 10 and U ZKi2 referred to as intermediate circuit voltage on the secondary side 20.

[0071] As shown in the example in Figure 2, both the excitation and the detection of the response can take place on the primary side 10. However, it is also possible to perform the excitation and the detection of the response on the secondary side 20. Furthermore, it is possible to perform the excitation on one side of the energy transfer system 100 (i.e., on the primary side 15 or the secondary side 25) and the detection of the response on the other side of the energy transfer system 100 (i.e., on the secondary side 25 or the primary side 15).

[0072] For stimulating the primary and / or secondary side (e.g., applying an excitation signal to or at the input of inverter module A1 or rectifier module A2) and for detecting a response (e.g., measuring a voltage and / or current behind inverter module A1 or rectifier module A2), it is possible to use means (in particular, voltage or current sources as well as voltage or current measuring devices) that are already standard in a conventional inductive charging or energy transfer system. Thus, the functionality of conventional inductive energy transfer systems can be easily expanded without additional components using commercially available microprocessors with a signal sampling rate of, for example, between 0.5 MHz and 5 MHz.

[0073] An evaluation unit (or a processor) can, for example, determine the poles and / or zeros of the measured response signal (especially the current signal) to determine the relative position of the transmission coils. A key advantage of this "sensorless" approach lies in the possible integration of position determination directly into existing energy transmission hardware. Neither additional components nor additional sensors are required. The position analysis can be performed independently either on the transmitter side (primary side 10) or on the receiver side (secondary side 20), without the two units having to actively interact. This is made possible by cleverly exploiting the flux-conducting and / or flux-shielding effects of materials (e.g., a vehicle chassis) in the immediate vicinity of the transmission coils 15 and 25.Figures 3a to 3e show examples of possible excitation signals that can be generated, in particular, using conventional full-bridge power electronics. It is understood that other signal forms are also possible depending on the choice of power electronics (half-bridge, multi-level converter, etc.). However, a full-bridge topology is preferably used. As can be seen from Figures 3a to 3e, the excitation can be continuous, constant, or pulsed. Figure 3a shows an example of continuous excitation using block pulse width modulation. Figure 3b shows an example of continuous excitation using pulse width modulation with a duty cycle of < 50%. Figure 3c shows an example of excitation using pulses or step functions in sections. Figure 3d shows an example of excitation using a discrete chirp signal.Figure 3e shows an example of an excitation using an excitation signal in the form of a delta-sigma modulated sine function. Example:

[0074] For example, in the setup shown in Figure 2, the secondary-side transmission coil 25 is to be aligned with the primary-side transmission coil 15. The position determination is to take place on the secondary side 20. In the initial state, the two coils 15 and 25 are sufficiently far apart so that the coils or charging units 15 and 25 do not yet electromagnetically influence each other. In other words, a magnetically decoupled state exists. While the secondary side 20 moves towards the primary side 10 or primary coil 15, the secondary coil 25 and the compensation network B2 are excited via the power electronics or power rectifier A2 with a voltage U2, which is applied to the power rectifier A2. If the excitation is pulsed, for example, the energy transmission system reacts with a transient impulse response and, after a decay time, decays back to the idle state. As soon as the idle state (orthe initial position) is reached again, a new impulse is given to the system, etc. The transient system response can be measured, for example, via the current I2(t) shown in Figure 2 or / . L2 (0 can be measured. Here, I2(t) denotes a current between the power rectifier A2 and the signal electronics D2. Furthermore, I L2 (t) a current between the compensation circuit B2 and the signal electronics D2.

[0075] As the secondary side 20 moves toward the primary side 10, the inductive coupling between the two transmission windings increases. Materials for magnetic flux guidance (e.g., ferrite, iron, etc.) and / or flux shielding (e.g., aluminum, copper, steel, etc.) can additionally reduce the self-inductances and L2 during the positioning of coils 15 and 25. The transient system response will differ according to the changed transfer behavior of the system depending on the coil positioning. This approach is based in particular on the fact that the frequency components in the transient process differ depending on the coil positioning. This is a direct consequence of the shift in the natural resonant frequencies of the system due to the inductive coupling of both coils 15 and 25 as well as the distortions of the inductances L and L2. In a similar way, the shift in the poles and / or zeros of the transfer functions can also be argued. The shift in the poles and / or zeros of, for example, the impedance Z2 = U2 / I2 leads to a change in the gain and / or delay of an input signal during coil alignment. In other words, the Bode diagram of the transfer function changes.For this reason, a periodic PWM signal, as shown in Figure 3a or Figure 3b, can also be used for position determination. A periodic PWM signal is a signal that is present longer than the settling time of the transmission system, so that the response signal reaches the steady state. This approach is therefore not about analyzing a transient settling process, but about observing the steady-state frequency response of the system. In other words, an excitation with a PWM signal of the fundamental frequency f0 experiences a position-dependent amplification and / or delay of the signal, according to the position-dependent Bode diagram.

[0076] For a transmission system with serial compensation on both sides, i.e., for the case where the compensation circuits B1 and B2 shown in Figure 2 comprise or are series-arranged capacitors, Figure 4a shows an example of a transient response of the current (t) on the primary side 15 of the energy transmission system 100. Figure 4b shows an example of a transient response of the current / 2(t) on the secondary side 25 of the energy transmission system 100. As can be seen from the diagrams in Figures 4a and 4b, measurement and simulation are in very good agreement. A PWM signal according to Figure 3a was used as excitation, which emerges abruptly from the rest position at time t = 0. Accordingly, (0) = Z2(0) = 0 with the switch-on time at t = 0. The transient response is characterized by a superposition of different frequency components. These frequency components can be made visible, for example, using a Fourier decomposition.As can be seen from Figures 4a and 4b, after approximately 0.3 milliseconds, the transient process has largely subsided, and the system is in a steady-state, or steady-state, state. Depending on the order of the energy transfer system, additional frequencies occur in this transient process, which may be damped to varying degrees. Figures 5a and 5b each show a pole-zero impedance diagram for an inductive charging system with LCC compensation on both sides, as is frequently used in automotive applications. when the secondary side is idle (i.e. load not connected). Figure 5a illustrates the case where the secondary side 20 is moved along a straight line trajectory over the center of the primary side 10. The position of the poles and / or zeros shifts, which is indicated in the positive imaginary half-plane by the dashed trace of the points. Figure 5b, on the other hand, illustrates the case where the secondary side 20 is moved in the same way over the primary side 10 along a parallel trajectory with an offset of 200 mm in the y-direction. The dashed trace of the poles and / or zeros is significantly different here than in the case of Figure 5a.Such a shift of the poles and / or zeros changes both the dynamic and stationary behavior of the energy transfer system 100 and can be used, as described above, for excitation by means of continuous or pulsed excitation signals for position determination.

[0077] It should be noted that in the above embodiment, the transmission coils 15 and 25 were magnetically decoupled in the initial state. However, this is not a mandatory boundary condition for position determination. The position determination can also be carried out if both coils are already inductively coupled. In the above example, a voltage signal (t / 2) was also used for the excitation. Depending on the circuit topology, however, excitation via a current signal (e.g. via the current / 2) is also possible. In the above example, excitation was carried out on the secondary side in order to determine the relative position with the help of a system response on the secondary side. It is just as possible to excite on the primary side in order to determine the relative position with the help of a system response on the primary side. However, the excitation and the evaluation of a system response do not necessarily have to take place on the same side.Rather, it is also possible to initiate the excitation on the primary side and evaluate it on the secondary side, or conversely, to initiate the excitation on the secondary side and evaluate it on the primary side. In the last two cases mentioned, in which excitation and evaluation take place on separate sides, information such as the phase position of the response relative to the excitation may be lost. However, this information can be transmitted, for example, via an external communication or synchronization interface. Alternatively, the loss of such information can be accepted if the position determination is already sufficiently accurate using the other available quantities or parameters. As already mentioned above, if the excitation and evaluation each take place on separate sides of the energy transfer system, depending on the topology of the energy transfer system, current and / or voltage transfer functions, e.g. of the form. for parameter identification and thus for determining the relative position of the primary and secondary sides.

[0078] Figure 6 shows a schematic flowchart or a routine for estimating the relative position between the primary and secondary sides of a contactless energy transmission system 100 according to a preferred embodiment of the invention. The routine is preferably executed cyclically. Based on an excitation signal that excites the power electronics of the energy transmission system 100 via the signal electronics, the energy transmission system 100 experiences a change in its energetic state, which triggers a transient transient response. The measurement and optional filtering of a system response or path response (in principle, multiple signals are also suitable for this) allows parameter identification, via which the relative position between the primary and secondary sides of the energy transmission system 100 can be estimated directly or indirectly.Direct methods for position estimation can, for example, be based on neural networks that directly convert an input signal (i.e., the system response or response signal) into a position estimate. Indirect methods comprise multiple steps, with the position estimation being performed through an intermediate step in parameter identification, e.g., based on a characteristic map with location-dependent coupling characteristics or inductance characteristics. Knowledge of the temporal progression of the secondary side kinematics, e.g., in automotive applications in the form of steering angle, tire position, wheelbase, wheel circumference, wheel speed, etc., can also be used to restrict the solution space of possible relative positions and improve the accuracy of the position estimation.

[0079] The present invention particularly utilizes a change in the electromagnetic system behavior due to a position-dependent alignment of the transmission coils. The use of flux-conducting and / or flux-shielding materials within the wireless energy transmission system and its immediate surroundings (e.g., vehicle floor, chassis, etc.) leads to a position-dependent change in the transmission behavior of the wireless energy transmission system. These changes can be determined using various methods for parameter identification. Sensorless position determination is achieved, in particular, by using current and / or voltage values ​​directly from the energy transmission system for position-dependent parameter identification. The energy transmission system can be single-phase or multi-phase (i.e., comprise two or more than two transmission coils). The contactless energy transmission system can be stationary (e.g.,The charging process can be either stationary (e.g., charging while stationary) or dynamic (e.g., charging while driving). The excitation signal for generating a transient system response can be applied to the primary and / or secondary side (especially with an active rectifier on the secondary side). Position estimation can be performed on both the primary and secondary sides. Position estimation can therefore be performed unilaterally, meaning no active participation of the other side (primary or secondary side) is required. This eliminates the need to meet a mutually agreed interoperability criterion to ensure minimum positioning. This feature can be particularly advantageous in dynamic charging systems, primarily for cost reasons. Furthermore, it eliminates the need for power supply to the other side at times when, for example, no parking maneuver is taking place (no "standby" supply required).Position determination can be achieved with or without energy transmission. It can be used in various wireless energy transmission applications (stationary, dynamic, etc.). No additional signal and / or power electronics are required. The existing hardware of an energy transmission system can be used, i.e., in particular, the transmission coils, the compensation network, the power rectifier, the power inverter, and its signaling, including signal electronics. In addition to the transmission coils of the energy transmission system, an assistance system for foreign object detection (metal object detection and / or live object detection) can also be used for position determination. By combining this with any existing vehicle sensors, lane-accurate tracking can be achieved.The basic principle of position estimation can be applied not only to inductive energy transfer systems, but also to capacitive energy transfer systems. The invention described herein can be used for both stationary charging and dynamic charging while driving. Position determination can be performed continuously or cyclically, and a trajectory can also be calculated from the estimated position profiles.

[0080] The present invention enables a cost-effective, in particular sensorless, estimation of the relative position and / or the relative movement of the primary and secondary sides of a contactless energy transfer system, in particular by exploiting the inherent physics of the energy transfer system itself. This simplifies the system design and reduces the installation effort with only low energy and computation requirements.

[0081] List of reference symbols

[0082] 10 Primary side (transmitter unit)

[0083] 15 Primary winding or primary coil

[0084] 20 Secondary side (receiver unit)

[0085] 25 Secondary winding or primary coil

[0086] 100 contactless energy transfer system

[0087] A1 Power inverter on the primary side

[0088] A2 Power rectifier on the secondary side B1 Compensation network on the primary side

[0089] B2 compensation network on the secondary side

[0090] D1 Signal electronics on the primary side

[0091] D2 Signal electronics on the secondary side E1 Excitation signal on the primary side

[0092] F1 Line response (response signal) on the primary side

[0093] L1 Inductance of the primary winding

[0094] L2 Inductance of the secondary winding

Claims

Patent claims 1. A method for determining a relative position of a primary side (10) and secondary side (20) of a contactless energy transmission system (100), comprising the steps: a) exciting the primary side (10) and / or the secondary side (20) of the energy transmission system (100) to generate a response signal (F1) of the primary side (10) and / or the secondary side (20) of the energy transmission system (100) that is dependent on the relative position to be determined; b) detecting the response signal (F1); and c) determining the relative position based on the detected response signal (F1).

2. Method according to claim 1, wherein the determination of a relative position is carried out without sensors.

3. Method according to claim 1 or 2, wherein at least one of steps a) to c) is carried out during a relative movement of the primary side (10) and the secondary side (20).

4. Method according to one of the preceding claims, wherein steps a) to c) are repeated cyclically.

5. Method according to one of the preceding claims, wherein a position estimation routine is carried out which comprises a plurality of cyclically repeating position estimates by means of steps a) to c).

6. The method according to claim 5, wherein the position estimation routine is performed during a relative movement of the primary side (10) and the secondary side (20) of the contactless energy transfer system (100).

7. Method according to one of the preceding claims, wherein a movement trajectory of the secondary side (20) is detected.

8. Method according to one of the preceding claims, wherein the primary side (10) comprises only a single primary coil; and / or wherein the determination of a relative position is carried out using only a single primary coil.

9. Method according to one of the preceding claims, wherein the detection of the response signal (F1) is carried out by a voltage and / or current measurement on the primary side (10) and / or the secondary side (20) of the energy transmission system (100).

10. Method according to one of the preceding claims, wherein the response signal (F1) reflects a transient transient response and / or a stationary frequency response of the primary side (10) and / or the secondary side (20) of the energy transmission system (100).

11. Method according to one of the preceding claims, wherein the response signal (F1) is based on a transient system response of the energy transmission system (100), and the determination of the relative position is based on a determination of frequency components of the transient system response; and / or wherein the detected response signal (F1) is based on a stationary system response of the energy transmission system (100), and the determination of the relative position is based on a determination of an amplitude and / or a phase position and / or at least one pole and / or zero of the stationary system response.

12. Method according to one of the preceding claims, wherein detecting the response signal (F1) comprises determining at least one transfer function of the energy transmission system (100) that is dependent on the relative position.

13. The method according to claim 12, wherein the determination of the relative position is based on a determination of poles and / or zeros of the at least one transfer function.

14. Method according to one of the preceding claims, wherein determining the relative position comprises determining one or more of the following parameters: - Inductance a primary winding (15) of the energy transmission system (100), - Inductance L2 of a secondary winding (25) of the energy transmission system (100), - Mutual inductance M of the primary winding (15) and secondary winding (25), - Coupling factor k of the primary winding (15) and secondary winding (25).

15. Method according to one of the preceding claims, wherein the determination of the relative position is carried out with the aid of at least one predetermined characteristic map and / or with the aid of a Kl algorithm, in particular with the aid of a neural network and / or a machine learning algorithm.

16. Method according to one of the preceding claims, wherein the method is a method for positioning a vehicle, and wherein, in particular, driving data read from the vehicle and / or vehicle data are taken into account for determining the relative position.

17. A computer program product comprising computer-readable instructions which, when loaded into a memory of a computer or processor and executed by the computer or processor, cause the computer or processor to perform a method according to any one of the preceding claims.

18. Device for determining a relative position of a primary side (10) and a secondary side (20) of a contactless energy transmission system (100), comprising: an excitation unit for exciting the primary side (10) and / or the secondary side (20) of the energy transmission system (100) and for generating a response signal (F1) of the primary side (10) and / or the secondary side (20) of the energy transmission system (100) that is dependent on the relative position to be determined; a detection unit for detecting the response signal (F1); and an evaluation unit for determining the relative position based on the detected response signal (F1).

19. Device according to claim 18, wherein the device is designed to carry out, in particular by means of a processor, a position estimation routine which comprises a plurality of cyclically repeating position estimations by means of the excitation unit, the detection unit and the evaluation unit.

20. Transmitter unit (10) and / or receiver unit (20) of a contactless energy transmission system (100), which comprises / comprises the device according to claim 18 or 19.

21. Use of the method according to one of claims 1 to 16 or of the computer program product according to claim 17 for parking a vehicle and / or for keeping the vehicle in lane.

22. Use of the device according to one of claims 18 and 19 or of the receiver unit (20) according to claim 20 in a vehicle as a parking assistant and / or as a lane keeping assistant.

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