DE102015224013A1 - Method for operating a monitoring device for monitoring an inductive energy transmission device - Google Patents

Abstract

The present invention relates to a method for operating a monitoring device for monitoring an inductive energy transmission device of at least one transmitting coil to at least one receiving coil spaced from the at least one transmitting coil, wherein the monitoring device comprises a data memory in the reference characteristic Uij, meas-ref depending on offset parameters dx, dy, dz are stored between the transmitting coil and the receiving coil, wherein in a first method step (A) the present offset parameters dx, dy, dz between the transmitting coil and the receiving coil are determined. In a second method step, a voltage Uij, meas induced by the magnetic field is measured in terms of magnitude and phase by means of the coil array. In a third method step (C), the determined measured values of the induced voltage Uij, meas are compared with reference characteristic diagrams Uij, meas-ref stored in the data memory and finally in a fourth method step (D) on the basis of the deviations between measured values of the induced voltage Uij, meas and Data storage stored reference maps Uij, meas-ref on the presence or absence of a foreign object closed.

Description

The present invention relates to a method for operating a monitoring device for monitoring an inductive energy transmission device.

State of the art

Electric vehicles and hybrid vehicles usually have an electrical energy storage, such as a traction battery, which provides the electrical energy for propulsion. If this electrical energy store is completely or partially discharged, then the electric vehicle has to control a charging station, at which the energy store can be recharged. So far, it is customary for this purpose that the electric vehicle is connected to the charging station by means of a cable connection at such a charging station. This connection must usually be made manually by a user. It is also necessary that charging station and electric vehicle have a mutually corresponding connection system.

Furthermore, occasionally wireless charging systems for electric vehicles or hybrid vehicles are known. For this purpose, an electric vehicle is parked above a transmitting coil (transmitting device) or a charging pad or charging device. This coil emits a high frequency alternating magnetic field. The alternating magnetic field is received by a receiving coil (charging coil or receiving device) within the vehicle and converted into electrical energy. By means of this electrical energy, a traction battery of the vehicle can then be charged. The publication DE 10 2011010 049 A1 discloses such a system for charging a vehicle battery, in which the energy is transmitted inductively.

Furthermore, the energy storage of the electric vehicle can also be used for feeding back. For this purpose, a cable connection or an inductive energy or power transmission can also be used.

In the wireless charging of a battery of an electric vehicle typically the transmitting coil of the transformer is either embedded in the street floor or formed as laid on the floor charging plate (charging pad) and is connected by means of suitable electronics to the mains. The receiver coil of the transformer is typically fixedly mounted in the underbody of the vehicle and in turn connected by suitable electronics to the traction battery of the vehicle. For energy transmission, the transmitting coil or primary coil generates a high-frequency alternating field which penetrates the receiving coil or secondary coil and induces a corresponding current there. Since, on the one hand, the transmitted power scales linearly with the switching frequency, and on the other hand the switching frequency is limited by the control electronics and losses in the transmission path, a typical frequency range of 30-150 kHz results.

Between the transmitting coil of the charging station and the receiving coil in the vehicle there is an air gap. Due to the required ground clearance of motor vehicles, this air gap is a few centimeters. Air gaps in the size of 3-30 cm are very common, unless by measures such as lowering the vehicle-fixed coil, the entire vehicle or lifting the stationary coil or a combination of these measures, an ideal small air gap is achieved. The alternating magnetic fields generated in the air gap during the transmission are suitable for inducing electrical eddy currents in any metallic or electrically conductive objects which are located in the air gap. Ohmic losses heat these so-called foreign objects. This heating is not only for personal safety, but also for the operational safety of the vehicle is a significant risk. Therefore, it is necessary to limit the heating of an inductive charging system either by limiting the magnetic field or any objects located in the air gap by suitable means to detect and then turn off the power transfer until they are removed, or you are no longer at risk.

Known methods of foreign object detection, for example, expediently consist of conventional metal detectors whose core element is one or more sensor coils. These methods are based on active excitation of the sensor coil / sensor coils and measurement of the change in the received signal in the presence of a metal object or the measurement of a change in the electrical properties of the sensor coil / sensor coils. However, in inductive charging / inductive power transmission, the use of conventional metal detection techniques is not trivial because of the strong magnetic field, so known metal object detection (MOD) techniques suggest either momentary shutdown of the energy transfer (and thus of the main magnetic field) or special sensor coil designs (e.g., meandering sensor coils) to perform a metal detection. Both are associated with significant disadvantages.

There is therefore a need for a more effective and less expensive monitoring device of inductive power transmission devices.

Disclosure of the invention

The inventive method with the characterizing part of claim 1 has the advantages that a short-term shutdown of the energy transfer (and thus of the magnetic main field) with respect to an efficient object recognition is no longer necessary.

According to the invention, in the method for operating a monitoring device for monitoring an inductive energy transmission device, at least one transmitting coil is separated from the at least one transmitting coil by at least one receiving coil, the monitoring device having a data memory in the reference characteristic diagrams U _{ij, meas-ref} in Dependent on offset parameters dx, dy, dz are stored between the transmitting coil and the receiving coil, in a first method step (A) the present offset parameters dx, dy, dz between the transmitting coil and the receiving coil are determined. In a second method step (B), a voltage U _{ij, meas} induced by the magnetic field is measured in terms of magnitude and phase by means of the coil array. In a third method step (C), the determined measured values of the induced voltage U _{ij, meas are} compared with reference characteristic diagrams U _{ij, meas-ref} stored in the data memory and finally in a fourth method step (D) on the basis of the deviations between measured values of the induced voltage U _{ij, meas} and stored in the data memory reference maps U _{ij, meas-ref closed} on the presence or absence of a foreign object. It is advantageous that the main magnetic field of the energy transfer is explicitly exploited in addition to the charging of a traction battery for metal detection and not only considered parasitic, as is the case with the known methods of the prior art. In other words, the main magnetic field is utilized and need not be turned off for metal detection, thereby ensuring continuous energy transfer.

The measures mentioned in the dependent claims advantageous refinements of the method specified in the independent claim are possible.

Advantageously, the voltage U _{ij, meas} induced by the magnetic field is measured by means of a coil array which is designed to monitor a gap between the at least one transmitting coil and the at least one receiving coil. By using a coil array, a significantly better spatial resolution can be achieved, whereby foreign objects in the field of energy transmission can be better localized.

It is also advantageous that the coil array rests on the transmitting coil or is installed on the top of the transmitting coil. By this arrangement, the monitoring device requires only a very small footprint and can also be run over by the vehicle to be loaded. Additionally / alternatively, another coil array can be installed on the vehicle-side receiver coil, so that monitoring is also ensured by the vehicle forth.

Furthermore, the individual coils of the coil array are made flat. Due to this design, the single coils can be installed very well in a flat charging pad. The geometry of the turns of the individual coils may alternatively have a circular, n-square, square, or cuboid shape.

The reference characteristics U _{ij, meas-ref} are advantageously stored as a function of offset parameters dx, dy, dz (and alternatively as a function of other operating parameters such as transmission power, etc.) in the data memory. These reference characteristic diagrams are advantageously determined by a calibration prior to delivery of the inductive energy transmission device and stored as a function of the offset parameters of the energy transmission device (of the coil system) dx, dy, dz.

Furthermore, it is advantageous that the monitoring device works passively. Due to the passive mode of operation, there is no need for any type of starting circuit for the monitoring device / coil array. As a result, the main magnetic field does not have to be switched off or the energy transfer must be interrupted in order to be able to carry out a metal detection. As a result, the energy transfer becomes more efficient and a continuous energy transfer can be ensured.

Furthermore, it is advantageous that the transmission coil is deactivated in the presence of a foreign object in the intermediate space or the power is reduced when an intrusion of an object has been detected.

Other features and advantages of the present invention will become apparent to those skilled in the art from the following description of exemplary embodiments, which are not to be construed as limiting the invention with reference to the accompanying drawings.

Brief description of the drawings

Show it:

1 a schematic representation of a vehicle and an inductive energy transfer device;

2 : a schematic representation of a coil array.

All figures are merely schematic representations of devices according to the invention or of their components according to embodiments of the invention. In particular, distances and size relationships are not shown to scale in the figures. In the various figures, corresponding elements are provided with the same reference numbers.

1 shows a schematic representation of a vehicle 19 , a device for inductive energy transfer 10 and a monitoring device 13 , The vehicle / electric vehicle / hybrid vehicle 19 is in a standing condition. The traction battery 18 is via the device for inductive energy transmission 10 loaded. In this regard, a transmitting coil / transmitting device 11 in the subsoil 20 let in or lies on the subsoil 20 on. The receiving coil / receiving device 12 is in the vehicle 19 arranged - preferably in the underbody of the vehicle 19 , Between transmission coil 11 and receiver coil 12 there is a gap 14 , also air gap 14 called. The monitoring device 13 is in this space 14 arranged and is preferably on the transmitting coil 11 on. The monitoring device 13 includes a coil array 15 , the single coils 16.1 . 16.2 , ... 16n having. During operation of the inductive power transmission device 10 becomes the magnetic main field that is between the transmitter coil 11 and the receiving coil 12 used for metal detection and not considered as parasitic. Furthermore, the inductive energy transmission device 10 a data store 17 on. In this data store 17 are reference maps U _{ij, meas-ref} in response to offset parameters dx, dy, dz resulting from the offset between transmit coil 11 and receiver coil 12 surrendered, filed. These reference maps are determined by calibration prior to delivery of the inductive energy transfer device using the coil array 15 the induced voltages U _{ij, meas-ref} for different positions of transmit coil 11 and receiver coil 12 be recorded. The spatial offset parameters dx, dy, dz result from the fact that the receiving coil horizontally in the X and Y direction relative to the ground 20 located transmitting coil 11 as well as vertically in the Z direction relative to the transmitting coil 11 is moved. When detecting the presence or absence of a foreign object, the procedure is as follows:
First, in a first method step A, the present offset parameters dy, dy, dz between the transmitting coil 11 and receiver coil 12 certainly. This measurement determines how much the receiver coil differs from the original calibration in the horizontal and vertical directions from the original calibration ex works. Subsequently, in a second method step B, a voltage U _{ij, meas} induced by the magnetic field is measured in terms of magnitude and phase by means of the coil array. In a third method step C, the determined measured values of the voltage U _{ij, meas} induced in the coil array are stored in the data memory 17 stored reference maps U _{ij, meas-ref} compared. Finally, in a fourth method step D, reference is made to the presence or absence of a foreign object on the basis of the deviation between measured values of the induced voltage U _{ij, meas} and reference characteristic maps stored in the data memory at U _{ij, meas-ref} . It is also quite another course of the process conceivable. Thus, first by means of the coil array in a method step A, the induced voltages U _{ij, meas} with magnitude and phase in all individual coils of the coil array 15 be measured. These measured values of the induced voltages U _{ij, meas} are finally compared with previously stored reference characteristic diagrams U _{ij, meas-ref} , the reference characteristic diagrams being calibrated prior to delivery of the system for inductive energy transmission 10 determined and stored as a function of the offset parameters dx, dy, dz of the energy transmission device. Now it must be distinguished. In the first case, the displacement situation that is actually present during the measurement is known. In this case, the relevant reference values can be taken directly from the stored maps (possibly by interpolation between interpolation points).

In the second case, the displacement situation that is actually present during the measurement is unknown. The offset situation (offset parameters dy, dy, dz) present during the specific measurement can be determined from the comparison with the stored reference characteristic diagrams. In this case, the possible deviation from the reference due to a metallic object is of no importance, because these are only detected on one sensor coil or a few sensor coils / individual coils of the coil array (FIG. 15 ) is present (depending on the size of the foreign object) and all other individual coils of the coil array deliver "correct" values (ie values that correspond to the absence of a foreign object). In the case of a significant deviation from the reference distribution of the stresses for the actual displacement situation determined in the present two cases, it is concluded that there is a metallic foreign object.

The distribution of the magnetic field to the various individual coils of the sensor array depends on the offset situation and on the currents excited in the two power transmission coils (transmitting coil / receiving coil). This method can also independent of the metal detection or Fremdobjekterkennung for Determining the coil offset between the transmitter coil 11 and receiver coil 12 used as well as for vehicle positioning are used.

2 shows a schematic representation of the coil array 15 , Same elements in terms of 1 are provided with the same reference numerals and are not explained in detail. Shown are the individual coils U11, U12, U13, etc., which act as sensor coils in the coil array, this being constructed as a coil plate.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011010049 A1 [0003]

Claims (7)

Method for operating a monitoring device ( 13 ) for monitoring an inductive energy transmission device ( 10 ) of at least one transmitting coil ( 11 ) to one of the at least one transmitting coil ( 11 ) spaced at least one receiving coil ( 12 ), the monitoring device ( 13 ) a data memory ( 17 ), in the reference maps U _{ij, meas-ref} in dependence on offset parameters dx, dy, dz between transmitting coil ( 11 ) and receiving coil ( 12 ) are stored, characterized in that - in a first method step (A), the present offset parameters dx, dy, dz between transmitting coil ( 11 ) and receiving coil ( 12 ), - in a second method step (B) a voltage induced by the magnetic field U _{ij, meas} by means of the coil array ( 15 ) is measured according to amount and phase, - in a third method step (C), the determined measured values of the induced voltage U _{ij, meas} with in the data memory ( 17 ) reference values U _{ij, meas-ref are} compared and - in a fourth method step (D) on the basis of the deviations between measured values of the induced voltage U _{ij, meas} and in the data memory ( 17 ) stored reference maps U _{ij, meas-ref is closed} to the presence or absence of a foreign object. Method for controlling a monitoring device ( 13 ) according to claim 1, characterized in that the induced by the magnetic field voltage U _{ij, meas} by means of a coil array ( 15 ), which is designed to provide a clearance ( 14 ) between the at least one transmitting coil ( 11 ) and the at least one receiving coil ( 12 ). Method for controlling a monitoring device ( 13 ) according to one of the preceding claims, characterized in that the coil array ( 15 ) on the transmitting coil ( 11 ) rests. Method for controlling a monitoring device ( 13 ) according to one of the preceding claims, characterized in that the individual coils of the coil array ( 15 ) are made flat and the geometry of the turns of the individual coils may alternatively have a circular, n-square, square or cuboid shape. Method for controlling a monitoring device ( 13 ) according to one of the preceding claims, characterized in that the reference characteristics U _{ij, meas-ref} in dependence on offset parameters dx, dy, dz in the data memory ( 17 ) are stored. Method for controlling a monitoring device ( 13 ) according to any one of the preceding claims, characterized in that the monitoring device operates passively, ie an active starting circuit is eliminated. Method for controlling a monitoring device ( 13 ) according to one of the preceding claims, characterized in that the transmitting coil ( 11 ) in the presence of a foreign object in the intermediate space ( 14 ) or the power is reduced if an intrusion of an object has been detected.

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