WO2019002244A1

WO2019002244A1 - Method for detecting a foreign object and device for inductive energy transfer to a portable terminal

Info

Publication number: WO2019002244A1
Application number: PCT/EP2018/067026
Authority: WO
Inventors: Ingo Pasewald; Kai WIEDICKE
Original assignee: Laird Dabendorf Gmbh
Priority date: 2017-06-27
Filing date: 2018-06-26
Publication date: 2019-01-03
Also published as: DE102017210835A1

Abstract

A device for inductive energy transfer to a portable terminal (2) and a method for detecting a foreign object, wherein the device (1) comprises at least one first winding structure (W1, W2, W3) for generating an electromagnetic field and an evaluation apparatus (13). The device (1) comprises or forms at least one support surface (15), wherein the device (1) comprises a first apparatus (8, 8a) for detecting a first temperature of at least a first region of the support surface (15) and at least a further apparatus (8, 8b) for detecting a further temperature of at least one further region of the support surface (15). At least in a charging mode, a profile over time of the first temperature is determinable as a first temperature profile, and a profile over time of the at least one further temperature is determinable as a further temperature profile. A foreign object (16) is detectable if the first temperature profile deviates by more than a predetermined measure from the further temperature profile.

Description

Method for detecting a foreign object and device for inductive

Energy transmission to a portable terminal

The invention relates to a method and a device for inductive

Energy transmission to a portable terminal. Furthermore, the invention relates to a method for detecting a foreign object in an inductive energy transmission to the portable terminal.

The inductive energy transfer to a portable terminal is known. In particular, such an energy transmission enables a cable-free energy transmission. As a rule, in such an energy transmission, a so-called transmitting coil generates an electromagnetic alternating field which is received by a receiving coil of the portable terminal. The alternating electromagnetic field induces an alternating voltage in the receiving coil. This AC voltage can, in particular after it has been rectified, be used to operate the portable terminal and / or to charge an energy store of the portable terminal.

It is problematic if a foreign object, in particular a metallic foreign object, is arranged between the transmitting and receiving coils. The alternating electromagnetic field can induce eddy currents in such a foreign object, whereby an effectiveness of the energy transfer is reduced and also a heating of the foreign object can take place. Such heating of a foreign object and the resulting heating of the environment may be undesirable.

Previously known was the detection of a foreign object by evaluation of a

Current account. In simplified terms, an input power of the device for generating the alternating electromagnetic field is determined or detected for this purpose. Furthermore, a received power of the device for receiving the electromagnetic alternating field is determined or detected. Furthermore, losses are determined. These power losses can be e.g. be determined in advance in a calibration process.

In particular, power losses can be operating point dependent.

If the sum of power loss and received power deviates from the input power by more than a predetermined amount, a foreign object is detected. The problem with this approach is that the power losses determined by a calibration are usually highly dependent on a relative position between the transmitting and receiving coil. Also, metallic elements of the terminal can

Reduce receive power, but such metallic elements are not foreign objects. Other influences, such as accuracy in determining the received power, can make this detection unreliable.

As a rule, therefore, threshold values which are used in the foreign object detection for the evaluation of the power balance, are chosen such that the above-mentioned disturbances do not lead or, to a small extent, to a misdetection. However, then the case may arise that an actually existing foreign object is not detected.

It is therefore the technical problem to provide an apparatus and method for inductive energy transmission to a portable terminal, which increase reliability in the detection of a foreign object.

The solution of the technical problem results from the objects with the features of claims 1 and 9. Further advantageous embodiments of the invention will become apparent from the dependent claims.

Proposed is a device for inductive energy transmission to a portable terminal, such as a mobile device, a tablet or another portable device. The device can be used in particular in a motor vehicle or automobile. Here, the device may be arranged in an interior of the motor vehicle, for example in a front seat or in a rear seat area. In this case, the device can be installed, for example, in a center console of the vehicle. However, the use of the device is not limited to use in a motor vehicle. Thus, the device can also be used as a stand-alone device, e.g. on a desk. Also, the use in other environments, especially in vehicles, e.g. on a ship, in a rail vehicle or in an airplane, is possible.

The device comprises at least one first winding structure for generating an electromagnetic field, which can also be referred to as a transmitting coil. This electromagnetic field is used for inductive energy transfer. In particular, this electromagnetic field is received by a winding structure of the portable terminal, which may also be referred to as a receiving coil, whereby a

AC voltage is induced in the winding structure of the portable terminal. This AC voltage can be rectified, for example via a rectifier of the portable terminal. The resulting rectified voltage can then be used to charge an energy storage device of the terminal and / or to operate the terminal.

The winding structure can have different geometries. In particular, the winding structure can be rectangular, circular, oval or another

have geometric structure. In this case, the winding structure can have a central center axis which, for example, has a central axis of symmetry

Winding structure can be.

As explained in more detail below, the device can also more than one

Windungsstruktur, in particular two, three or more than three Windungsstrukturen, so transmit coils include. Furthermore, the device may comprise at least one device for generating an operating voltage for the first winding structure. This device may in particular be an inverter. This can generate from an input DC voltage an output AC voltage for operation or for feeding the first winding structure, because the output AC voltage has desired properties, in particular a desired amplitude and frequency.

The device for generating the operating voltage can thus be electrically connected to the first winding structure.

Furthermore, the device comprises at least one evaluation device. This can be designed for example as a microcontroller. The evaluation device can be part of a control and evaluation device. The control and evaluation device can in particular control an operation of the device for generating the operating voltage. In particular, switching times of switching elements of an inverter can be set by the control and evaluation devices. Furthermore, the control and evaluation device can activate or deactivate a charging operation. In a loading operation can be generated the previously explained electromagnetic alternating field. When the charging mode is deactivated, no alternating electromagnetic field is generated.

Furthermore, the device has at least one bearing surface or forms it. For example, the device may comprise a housing, wherein the housing, in particular a surface of the housing, has or forms the bearing surface. The housing may have, for example, an upper shell and a lower shell. An upper side of the upper shell can in this case have or form the contact surface.

The support surface is used for storage or storage of the portable device.

According to the invention, the device comprises a first device for detecting a first temperature of at least a first subregion of the bearing surface and at least one further device for detecting a further temperature of at least one further subregion of the bearing surface. The support surface may in this case be formed by a plastic body. The first and the further subarea may be different subregions of the bearing surface. In this case, it is possible for the subregions to overlap at least partially. However, it is also possible that the subareas do not overlap. In other words, the first

Device for detecting a temperature and the further device for detecting a temperature from each other different detection ranges.

A device for detecting a temperature may, for example, as

Temperature sensor may be formed. In particular, the device for detecting a temperature may be arranged such that it is thermally connected to at least a portion of the support surface. In other words, a temperature or a temperature change of the partial area can be detected by a corresponding device for detecting a temperature.

In particular, the number of means for detecting a temperature may be equal to the number of winding structures. In this case, each winding structure can each be assigned a device for detecting a temperature. Of course, it is also possible that a Windungsstruktur more than a device for detecting a temperature or no means for detecting a temperature are assigned. Further, in particular by the evaluation device, at least in a loading operation as a first temperature profile, a time course of the first temperature and as a further temperature profile a temporal course of the at least one further temperature can be determined. In particular, temperature values of the first temperature and of the further temperature can be determined at a plurality of detection times. For this purpose, the evaluation device can be signal and / or data related to the means for detecting a temperature. Next, the evaluation can a

Memory device include, wherein in the memory device temperature values and optionally the detection times of these temperature values can be stored.

Furthermore, in particular likewise by the evaluation device, a foreign object can be detected if the first temperature profile deviates from the further temperature profile by more than a predetermined amount, in particular if at least one

Property of the first temperature profile deviates by more than a predetermined amount of a corresponding property of the further temperature profile.

If the temperature curves do not differ or no longer differ from each other by a predetermined amount, then it can be assumed that there is no foreign object which, during a loading operation, leads to different temperature gradients in the various subregions of the bearing surface, in particular to a different degree of heating in these subregions would. If, for example, the entire environment of the device heats up, for example an interior of the motor vehicle, both temperature profiles become one without any foreign object present

Represent temperature rise, but do not deviate from each other by more than a predetermined amount. However, if a foreign object is arranged on one of the partial areas or in the vicinity of one of the partial areas, the corresponding temperature in the charging mode can increase more than the temperature of the remaining partial area.

In this case, it can be assumed that a foreign object is dimensioned only so large that a foreign object leads only to the temperature change of one or more partial areas, but not all partial areas. This results in an advantageous manner a reliable detection of a foreign object, which is arranged on the support surface or in spatial proximity to such a portion.

In a further embodiment, a gradient of the first temperature profile can be determined as the first gradient at at least one point in time, and a gradient of the further temperature profile can be determined as a further gradient. The gradients of the temperature profiles determined at the same time can also be referred to as corresponding gradients.

In other words, at the at least one point in time is a value of a gradient of the first temperature profile and a value of a gradient of the other

Temperature course determinable. The gradient may in particular denote the value of a time derivative of the temperature profile.

Furthermore, a foreign object can be detected when the first gradient deviates from the further gradient by more than a predetermined amount, in particular when the amount of a difference between the corresponding gradients is greater than a predetermined threshold value.

Of course, the first gradient and the further gradient can each be determined at a plurality of mutually corresponding points in time. In particular, therefore, a temporal course of the gradient of the first temperature profile and a time profile of the gradient of the further temperature profile can thus be determinable.

Furthermore, a foreign object can be detected if at least one, more than one

predetermined proportion, e.g. more than 10%, 20% or 50%, or all of the set of mutually corresponding gradients differ by more than a predetermined amount. Thus, a foreign object can be detectable if the time profile of the gradient of the first temperature profile and the time profile of the gradient of the further temperature profile deviate from one another by more than a predetermined amount.

The predetermined measure or the predetermined threshold can in this case z. In test or calibration passes. This advantageously results in a simple implementation of the reliable detection of foreign objects.

In a further embodiment, at least part of a device for detecting a temperature, ie the first temperature or the further temperature, is arranged under or on the support surface. In particular, a measured value sensor of the device for detecting a temperature can be arranged below or on the support surface. This may mean that the part is arranged in front of the support surface or at the same position as the support surface along a vertical direction, which may be oriented perpendicular to the support surface or parallel to a central axis of the winding structure and from the winding structure to the support surface. This results in

Advantageously, a simple structural integration of the devices for detecting a temperature, which at the same time space requirements for the entire

Device can be reduced.

In a further embodiment, at least one part, in particular the measured variable pick-up, of a device for detecting a temperature is arranged above the at least one winding structure. For example, the part may be arranged between the support surface and the winding structure. Also, the part of the means for detecting a temperature between the winding structure for generating the

be arranged electromagnetic field and a placed on the support surface portable terminal. This results in an advantageous manner, a spatial proximity of the means for detecting a temperature to the support surface and thus a reliable detection of the temperature or the change in temperature.

In a further embodiment, the at least one part, in particular the

A measured quantity pickup, the first means for detecting the first temperature in a common projection plane, which is arranged perpendicular to a central axis of the first winding structure, disposed within the first winding structure. This may mean that the part of the device for detecting a temperature in the projection plane is arranged in a region which is surrounded or surrounded by an envelope of the winding structure in the projection plane.

This results in an advantageous manner that a high reliability for a detection of foreign objects is ensured, directly above the first Winding structure are arranged and thus the electromagnetic alternating field, which is generated by this first winding structure are exposed to the maximum extent and therefore can heat relatively strong.

In a further embodiment, the device comprises at least one further winding structure, wherein at least one part, in particular the measured variable pickup, of the further device for detecting the further temperature in a common projection surface, which is arranged perpendicular to a central axis of the further winding structure, within the other Winding structure is arranged.

Thus, at least a part of the device associated with a winding structure for detecting a temperature in a common projection surface, which is arranged perpendicular to a central axis of the corresponding winding structure, may be arranged within the winding structure. As a result, a foreign object can be detected with a very high reliability, which to the greatest extent possible

Subject to electromagnetic alternating field, which is generated by a winding structure.

In a further embodiment, the device has at least one

Communication device for communication with the portable terminal on. The communication device can serve for the transmission of data and / or signals. For example, data that is sent by the portable terminal can be received via the communication device. This data may, for example, encode information about a received power. The communication may be a so-called in-band communication, that is a communication via a user channel used by the terminal. Alternatively, the communication may be a so-called out-band communication, that is a communication via a secondary channel used by the terminal. The communication can also be a load-modulation-based communication. Further, the communication may be wireless communication, e.g. B. a Bluetooth ™ -based communication.

The communication device can data and / or signaling technology with the

Be connected evaluation. The communication device advantageously makes it possible to evaluate a power balance, which will be explained in more detail below, wherein it can be used in addition to the foreign object detection.

In a further embodiment, a transmission power, a received power and a power loss can be determined, in particular during charging operation. A transmission power can in particular be determinable by a device for detecting or determining a transmission power. The transmission power can in this case an input power of

be previously explained means for generating an operating voltage for the winding structure for generating the alternating electromagnetic field. Also, the transmission power may be equal to an output power of this device for generating an operating voltage. The portable terminal may include means for detecting or determining a reception power. The received power may in this case be an input or output power of a rectifier, wherein the induced AC voltage in the winding structure for receiving the rectifier by the rectifier

Electromagnetic alternating field is rectified.

A power loss may in particular include losses in the inductive energy transfer, in particular in or by further electrical or electronic components. A power loss can be determined in test or calibration runs and then stored for later use. A power loss can in particular be determined depending on the operating point and stored with an assignment to the operating point. In this case, an operating point can be determinable, for example by the evaluation device, wherein a power loss can then be determined as a function of the operating point. An operating point may, for example, be given by one or more of the following parameters: current in the

Transmitting coil (s), transmission power, received power, input voltage of the device for generating an operating voltage for the first winding structure.

Furthermore, a foreign object, in particular additionally, can be detected as a function of an evaluation of a power balance. In particular, a foreign object can only be detectable if, in addition to the deviation between the temperature profiles, the sum of power loss and received power deviates from the transmission power by more than a predetermined amount. The predetermined amount can here

be dependent on the operating point. It is conceivable, for example, that a foreign object is detected only if the foreign object is detected as a function of the evaluation of the power balance and if the first temperature profile deviates from the further temperature profile by more than a predetermined amount.

In this case, the determination of the deviation between the first temperature profile and the further temperature profile, in particular the determination of the deviation between the previously explained gradients, can be carried out in terms of time, but preferably in terms of time after the evaluation of the power balance. In particular, it is possible that the determination of the deviation between the first

Temperature profile and the further temperature profile is only performed when a foreign object has been detected potentially depending on the evaluation of the power balance, in particular so if the sum of power loss and

Receiving power differs by more than a predetermined amount of the transmission power.

This results advantageously in a redundancy in the foreign object detection and thus increased reliability of the foreign object detection.

Further proposed is a method for detecting a foreign object in an inductive energy transmission to a portable terminal. In this case, the method can be carried out in particular by means of a device according to one of the embodiments explained in this disclosure. In this case, a time profile of a first temperature of at least one first subarea of the bearing surface and, as a further temperature curve, a temporal course of a further temperature of at least one further subarea of the bearing surface are determined as the first temperature profile. Furthermore, a foreign object is detected when the first temperature profile deviates from the further temperature profile by more than a predetermined amount. This and

corresponding advantages have already been explained above.

In a further embodiment, a gradient of the first temperature profile is determined as the first gradient at at least one point in time, and a gradient of the further temperature profile is determined as a further gradient, wherein the foreign object (16) is detected when the first gradient exceeds the first gradient by more than a predetermined amount deviates further gradient. This and corresponding benefits have been previous already explained. Also, the first gradient curve may be a temporal course of the first gradient and, as a further gradient curve, a time curve of the further gradient

Gradients are determined, wherein a foreign object is detected when the first gradient deviates by more than a predetermined amount of the further gradient.

In a further embodiment, a transmission power, a reception power and a power loss are determined. Furthermore, the foreign object is detected as a function of an evaluation of a power balance. This and corresponding advantages have been explained above.

In particular, in this case a transmission power can be detected or determined. Furthermore, a power loss can be detected or determined. Also, a received power can be detected or determined, wherein information about the received power can be transmitted from the portable terminal to the device, in particular via the described communication device.

The invention will be explained in more detail with reference to an embodiment. The figures show:

1 shows a schematic cross section through an inventive

Device,

2 is a schematic plan view of an apparatus according to the invention,

Fig. 3 is a schematic flow diagram of a method according to the invention and

4 shows a schematic flowchart of a method according to the invention in a further embodiment.

Hereinafter, like reference numerals designate elements having the same or similar technical features. Fig. 1 shows a schematic block diagram of a device 1 for inductive

Power transmission to a portable device 2. The portable device can

for example, be a mobile phone. The device 1 can be used for example in a motor vehicle. In particular, the device in a

Center console of the motor vehicle may be arranged.

The device 1 comprises a housing 3, which has an upper shell 4 and a

Lower shell 5 has. An upper side of the upper shell 4 forms a bearing surface 15 for the portable terminal 2.

Furthermore, the device 1 comprises a first printed circuit board 6. An antenna structure 7 and temperature sensors 8, 8a, 8b, 8c are arranged on or in this printed circuit board 6. Furthermore, the device 1 comprises a second printed circuit board 9 on or in this second

Circuit board 9, a first winding structure W1, a second winding structure W2 and a third winding structure W3 are arranged. These winding structures W1, W2, W3 serve to generate an electromagnetic alternating field. This

alternating electromagnetic field can in turn be received by a winding structure WR of the portable terminal 2, whereby an AC voltage in this winding structure WR is indexed.

Furthermore, the device 1 comprises a first shielding plate 10 and another

Shielding plate 1 1. Furthermore, the device 1 comprises a further printed circuit board 12, wherein in or on the further printed circuit board 12, a control and evaluation device 13 is arranged or formed. Furthermore, the device 1 comprises a heat sink 14.

Shown is a vertical direction z. This is oriented perpendicular to the support surface 5. Also, the vertical direction z is oriented parallel to not shown central center axes of the winding structures W1, W2, W3. The vertical direction z is from the

Lower shell 5 oriented to the upper shell 4. Thus, the vertical direction z is also oriented by the winding structures W1, W2, W3 towards the bearing surface 15. Along the

Vertical direction z are the lower shell 5, the heat sink 14, a shield plate 1 1, the other circuit board 12, the shield plate 10, the circuit board 9, the circuit board 6 and the upper shell 4 one above the other, so arranged sequentially. Not shown in Fig. 1 are data and signaling connections as well

Connections for energy transfer between the individual elements of the

Device 1, for example, between the control and evaluation device 13 and the temperature sensors eighth

By means of the control and evaluation device 13, an operation of the winding structures W1, W2, W3 can be controlled. In particular, by means of the tax and

Evaluation a charging mode are activated, wherein in the loading mode a

AC voltage with desired properties (amplitude, frequency) to at least one, but also several, winding structures W1, W2, W3 can be applied. As a function of this applied operating voltage, the one winding structure W1, W2, W3 generates or generates the plurality of winding structures W1, W2, W3

electromagnetic alternating field.

In Fig. 1 it is shown that the temperature sensors 8, 8a, 8b, 8c along the

Vertical direction z are arranged in front of the support surface 15. In other words, the temperature sensors 8, 8a, 8b, 8c are arranged under the bearing surface 15. Further, the temperature sensors 8, 8a, 8b, 8c are behind the vertical direction z

Winding structures W1, W2, W3, in other words above this

Winding structures W1, W2, W3 arranged. The upper shell 4 and the printed circuit board 6 may consist of thermally conductive material, in particular of plastic. Thus, the temperature sensors 8a, 8b, 8c are thermally connected to the support surface 15.

Schematically represented (by dashed lines) are detection ranges of the individual temperature sensors 8a, 8b, 8c.

It can thus be seen that a first temperature sensor 8a can detect a temperature of a first subregion of the bearing surface 15. A second temperature sensor 8b can detect a temperature of a second subregion of the bearing surface 15. Accordingly, a third temperature sensor 8c can detect a temperature of a third subregion of the bearing surface 15.

The subregions may overlap at least partially. However, it is also possible that the subregions do not overlap. However, it is

desirable that the subregions a so-called loading area or active area of the Cover pad 15 as completely as possible. The loading surface of the support surface 15 may denote a partial surface for which an inductive energy transfer with desired properties is possible if a portable terminal on this

Loading surface is hung up. It is possible that the entire support surface 15 the

Cargo bed forms.

Also shown is a foreign object 16, in particular a metallic foreign object 16, which is likewise arranged on the support surface 15.

By means of the temperature sensors 8, 8a, 8b, 8c, in particular in a charging operation, a temperature of the corresponding partial regions of the support surface 15 can be detected. Further, for example by means of the control and evaluation device 13, a temporal course of temperature values can be determined, which are generated by the individual temperature sensors 8a, 8b, 8c during the charging operation. Furthermore, a gradient curve can be determined for these individual temperature profiles.

In the scenario illustrated in FIG. 1, it can be assumed that the gradient profiles, which are determined from the temperature profiles of the temperature values of the first and second temperature sensors 8a, 8b, are the same or differ from each other by no more than a predetermined amount. The electromagnetic

Alternating field, which is generated for example by the third winding structure W3 for inductive energy transmission to the portable terminal 2, the foreign object 16 will be exposed. In particular, this foreign object 16 will heat up due to the electromagnetic alternating field. Therefore, the gradient profile determined from the time history of the temperature values of the third temperature sensor 8c becomes more than a predetermined amount from the others

Deviate gradient curves.

It is advantageous in this case to evaluate gradients, since in addition to the heating by the foreign object 16, temperature changes in the environment of the device 1 that are not caused by undesired foreign objects can occur.

For example, a heating of the interior temperature of a passenger compartment of a vehicle, for. B. by a heater. The control and evaluation device 13 detects a deviation of at least one value of the first gradient of at least one value of the other

Gradient course by more than a predetermined amount, so a foreign object can be detected. If a foreign object is detected, then an activated charging operation can be deactivated or interrupted for a predetermined period of time. The values of the gradients can be determined for or at a common time.

Fig. 2 shows a schematic plan view of the device 1 shown in Fig. 1, wherein the upper shell 4, the antenna structure 7, the magnetic shield plates 10, 1 1, the circuit board 12, the heat sink 14 and the lower shell 3 are not shown.

Visible are the three winding structures W1, W2, W3, which are formed rectangular in the illustrated embodiment. Further shown are the

Temperature sensors 8, 8a, 8b, 8c.

It can be seen that in a common projection surface, which may be oriented perpendicular to the vertical direction z shown in FIG. 1, the first temperature sensor 8a is included in the first winding structure W1. In particular, the first one

Temperature sensor 8a arranged in a plane that in the common

Projection of the first winding structure W1 is included. Accordingly, the second temperature sensor 8b of the second winding structure W2 in the

includes common projection screen. Furthermore, the third temperature sensor 8c of the third winding structure W3 is also included. Here, however, only one

Temperature sensor each having a winding structure W1, W2, W3 includes.

Shown again by dashed lines are the subareas of the support surface whose temperature can be detected by the corresponding temperature sensor 8, 8a, 8b, 8c.

In particular, the temperature sensors are arranged centrally or centrally above a corresponding winding structure W1, W2, W3. This may mean that the central center axis of the winding structure W1, W2, W3 intersects the temperature sensor 8a, 8b, 8c associated with the respective winding structure W1, W2, W3.

It is further shown that the winding structures overlap at least partially in the common projection plane. 3 shows a schematic flow diagram of a method according to the invention.

In a first step S1, a charging operation is activated, for example by the control and evaluation device 13 shown in FIG. 1. In this case, the charging operation can be activated such that one, several or all winding structures W1, W2, W3 generate an electromagnetic alternating field. Preferably, however, an electromagnetic alternating field is generated only by means of a single winding structure W1, W2, W3. In particular, an alternating electromagnetic field is generated by means of the winding structure W1, W2, W3, through which the most effective and loss-free

Power transmission to the portable terminal 2 is possible. An identification of the corresponding winding structure W1, W2, W3 can in this case take place before the first step S1 and is not part of this invention.

In a second step S2, temperature values of the individual temperature sensors 8a, 8b, 8c are detected during the charging operation. Thus, temporal courses of these temperature values are recorded. Furthermore, a gradient profile of this time profile is determined, for example by means of the control and evaluation device 13. In a third step S3, it is determined whether at least one of these gradient curves is at least more than a predetermined amount, which can be determined, for example, by tests or calibration passes deviates from another gradient.

If such a deviation is detected, then a foreign object 16 (see FIG. 1) is detected. In this case, a charging operation can be deactivated or interrupted.

4 shows a schematic flow diagram of a method according to the invention according to a further embodiment. Here, the first step S1 corresponds to the first step S1 shown in FIG. In a second step S2 becomes a

Current account determined and evaluated. In this case, in particular by means of the control and evaluation device 13, an input power can be determined, wherein the input power in the charging mode, an input power of a not shown

Inverter is one of the operating voltage for one or more of the

Winding structures W1, W2, W3 generated. Next can by means of the tax and

Evaluation device 13 a power loss can be determined. The power loss can be dependent on the operating point, so in particular dependent on the current in the Transmit coils and receive power. Power losses for operating points can be determined and stored, for example, in a calibration pass or in test procedures.

Furthermore, an output power can be determined. This may be, for example, a power provided by a rectifier of the portable terminal 2, the rectifier (not shown) rectifying the voltage induced in the winding structure WR of the portable terminal 2. The output power can be z. B. transmitted from the terminal 2 via a communication device, not shown, to the control and evaluation device 13. If the input power deviates by more than a predetermined amount from the sum of the power loss and the output power, a potential foreign object 16 can be detected in the second method step S2. If no potential foreign object is detected, the power balance can in particular be evaluated again, ie periodically, after a predetermined period of time.

Alternatively, the power balance can be continuously evaluated. Further, in particular simultaneously, in the second method step S2 temporal courses of the temperature sensors 8a, 8b, 8c can be detected and the corresponding ones

Gradient gradients are determined.

Only if a potentially existing foreign object 16 is detected on the basis of the evaluation of the power balance in the second method step S2, can a third step S3 be carried out, which corresponds to the third step S3 shown in FIG. In the second step S2, the above-described detection and evaluation of the gradient curve is carried out in this case.

Claims

claims

1 . Device for inductive energy transmission to a portable terminal (2), wherein the device (1) at least one first winding structure (W1, W2, W3) for generating an electromagnetic field and an evaluation device (13), wherein the device (1) at least one Bearing surface (15) or forms,

characterized in that

the device (1) has a first device (8, 8a) for detecting a first temperature of at least a first subregion of the bearing surface (15) and at least one further device (8, 8b) for detecting a further one

Temperature of at least one further portion of the support surface (15), wherein at least in a loading operation as a first temperature profile, a time course of the first temperature and as a further temperature curve, a time course of at least one further temperature can be determined, wherein a foreign object (16) is detectable if the first temperature profile deviates from the further temperature profile by more than a predetermined amount.

2. Device according to claim 1, characterized in that at least

a gradient of the first temperature profile can be determined as a first gradient and a gradient of the further temperature profile can be determined as a further gradient, the foreign object (16) being detectable if the first gradient deviates from the further gradient by more than a predetermined amount.

3. Apparatus according to claim 1 or 2, characterized in that at least part of a device (8, 8a, 8b, 8c) for detecting a temperature under or on the support surface (15) is arranged.

4. Device according to one of the preceding claims, characterized

characterized in that at least a part of a device (8, 8a, 8b, 8c) for detecting a temperature is arranged above the at least one winding structure (W1, W2, W3).

5. Device according to one of the preceding claims, characterized in that at least part of the first means (8, 8a) for detecting a first temperature in a common projection surface, which is arranged perpendicular to a central axis of the first winding structure (W1), within the first winding structure (W1) is arranged.

6. Device according to one of the preceding claims, characterized in that the device (1) comprises at least one further winding structure (W2, W3), wherein at least a part of the further device (8, 8b, 8c) for detecting a further temperature in a common projection surface, which is arranged perpendicular to a central axis of the further winding structure (W2, W3), within the further winding structure (W2, W3) is arranged.

7. Device according to one of the preceding claims, characterized

characterized in that the device (1) at least one

Communication device for communication with the portable terminal (2).

8. Device according to one of the preceding claims, characterized

in that a transmission power, a received power and a power loss can be determined, wherein the foreign object (16) is detectable as a function of an evaluation of a power balance.

9. A method for detecting a foreign object (16) in an inductive

Energy transmission to a portable terminal (2), being the first

Temperature profile, a time course of a first temperature of at least a first portion of a support surface (15) and as a further temperature profile, a time course of a further temperature of at least one other

Part of the support surface (15) is determined, wherein the foreign object (16) is detected when the first temperature profile deviates by more than a predetermined amount of the further temperature profile.

10. The method according to claim 9, characterized in that a gradient of the first temperature profile is determined as the first gradient at at least one point in time and a gradient of the further temperature profile is determined as a further gradient, wherein the foreign object (16) is detected when the first gradient deviates from the further gradient by more than a predetermined amount. A method according to claim 9 or 10, characterized in that a

Transmitting power, a received power and a power loss are determined, wherein the foreign object (16) in dependence of an evaluation of a

Current balance is detected.