DE102014222486A1 - Method for monitoring an inductive transmission path and charging system for inductively charging an electric vehicle - Google Patents

Abstract

The invention provides a method for monitoring an inductive transmission path to living objects, comprising an inductive transmission path and a locally the inductive transmission line penetrating and surrounding security area, comprising the following steps: with switched inductive transmission line monitoring the security area on penetrating objects and switching off the inductive transmission path upon detection a penetrating object in the security area; When the inductive transmission path is switched off, monitoring of the safety area for the presence of a living object within the safety area and blocking of the inductive transmission path upon detection of a living object within the safety area. The invention also relates to a charging system for inductively charging an electric vehicle with an inductive transmission path, a security area, which penetrates and surrounds the inductive transmission link, a device for monitoring the security area on living objects with a control device and sensors, and a device for providing the charging power which is controlled by the security object monitoring device for living objects, the device for monitoring the security area for living objects executing the above method.

Description

State of the art

The invention relates to methods for monitoring an inductive transmission path and a charging system for inductive charging of an electric vehicle according to the preamble of the independent claims.

In the so-called inductive charging of electric vehicles, the energy required for charging the vehicle battery is not transferred to the vehicle via a charging cable (conductive charging), but via a transformer with a large air gap. Here, typically, the primary coil of the transformer is either embedded in the street floor or shaped as laid on the floor pallet and is connected by means of suitable electronics to the power grid. The secondary coil of the transformer is typically fixedly mounted in the underbody of the vehicle and in turn connected by suitable electronics to the vehicle battery. For energy transfer, the primary coil generates a high-frequency alternating magnetic field, which penetrates the secondary coil and induces a corresponding current there. Since, on the one hand, the transmittable 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, this results in a typical frequency range of 30-150 kHz.

The alternating magnetic fields generated in the air gap during the transmission are suitable for inducing electrical eddy currents in any metallic objects that are located there. Ohmic losses heat up these so-called foreign objects. This heating is not only for personal safety (protection against contact), but also for the operational safety of the vehicle is a significant risk. Furthermore, biological objects such as animals, human body parts, living objects must be generally recognized in order not to expose them to the high magnetic fields , Therefore, detection of living objects is a necessary part of an inductive charging system.

In principle, various types of motion detectors are suitable for detecting objects, eg passive infrared sensors, Doppler radar, ultrasound sensors and object recognition methods such as laser scanners, video cameras, stereo cameras or thermal imaging cameras. Special challenges in many processes are:
the confinement of the detection area to the area of high magnetic fields;
the distinction of critical (living) from other objects;
the sensitivity to environmental conditions such as moisture, snow or ice.

The US 2008/0103660 A1 discloses a system for detecting living objects in the interior of a vehicle. However, the sensors used are based on the deformation of the sensors, so that they are not suitable for the detection of living objects in the danger zone of an inductive charging station.

From the WO 01/17838 A1 a method for monitoring a danger zone by means of a camera is known. The method compares images of a saved safe state with current images. A detection of living objects is not provided.

Disclosure of the invention

The present invention discloses a method for monitoring an inductive transmission path to living objects, comprising an inductive transmission path and a locally the inductive transmission line penetrating and surrounding security area, being monitored with inductive transmission path, the security area on penetrating objects and the inductive transmission path is switched off when an intruding object is detected in the security area, and when the inductive transmission path is switched off, the security area is monitored for the presence of a living object within the security area, and the inductive transmission link is blocked on detection of a living object within the security area. Due to the particularly advantageous division of the monitoring into a short-term observation measuring the detection of penetrating objects of any kind and a long-term observation for the detection of living objects located in the security area, a particularly reliable monitoring of the inductive transmission path can be ensured. It is also advantageous to split the fast measurement when the inductive transmission path is switched on and the slow measurement when the inductive transmission path is switched off. This avoids any endangering of living objects such as birds, dogs and cats as well as humans since the inductive transmission path can be switched off very quickly according to the invention. The long measurement before switching on the inductive transmission path has the advantage that any living objects in the air gap of the inductive transmission path can be reliably detected, so that they can not be endangered by switching on the inductive transmission path. An electric charging power for an electric vehicle via the transmitted inductive transmission path. Electric vehicles require high charging power, which results in high field strengths in the inductive transmission path. Here, the method according to the invention can advantageously exploit its advantages in terms of safety.

In one embodiment, the inductive transmission path is switched on again when it is detected that no living object is in the security area. This measure advantageously increases the charging efficiency, since the time available for charging is particularly well utilized.

In a further embodiment, the inductive transmission path is switched off when the vehicle is fully charged. This advantageously increases safety, since the inductive transmission path is only switched on when it is really needed.

In one embodiment, the security object monitoring device for the security area monitoring intruding objects measures a time range of 0 s to 5 s. This period of time has the advantage that the inductive transmission path can be switched off quickly as soon as an object enters the security area. Particularly preferably, the measurement time is less than 2 s, so that a particularly fast shutdown of the inductive transmission path can be ensured.

In one embodiment, the living object security surveillance device measures a time range of 5 seconds to 30 seconds for monitoring the security area for living objects. Through this long period of time, a living object can be reliably detected, even if it is breathing very slowly and the respiratory rate is correspondingly low. Even at very low frequency, the sampling theorem is satisfied, and advantageously ensures detection of the living object. Particularly preferably, the measuring time is more than 10 s, so that the detection of living objects can be accomplished even safer.

In a preferred embodiment, the corresponding measurements are analyzed for object distances or maximums of the object distance distribution, and time series are composed of the object distances or maxima of the object distance distribution of several successive measurements, these are Fourier-transformed and analyzed for frequencies which indicate a living object. This measure advantageously ensures good recognition of the relevant frequencies and is easily feasible with a control unit of today's computing power.

In another embodiment, the device for monitoring the safety area on living objects transforms the corresponding measurement of the time range, and analyzes the resulting distance distribution to maxima. From the maxima of several consecutive measurements, the security surveillance device collates a time series on living objects, in turn Fourier transforms them and analyzes the result for frequencies indicative of a living object. This measure also advantageously ensures good recognition of the relevant frequencies and is easily feasible with a control unit of today's computing power.

In a particularly preferred embodiment, the frequencies indicative of a living object are frequencies of respiration or the pulse of the living object. The respiratory rate of a living object is e.g. between 0.2 Hz and 0.6 Hz. The pulse frequency is correspondingly higher and can be assumed to be 1 Hz to 4 Hz. The focus on these frequencies advantageously simplifies the detection of a living object substantially and requires correspondingly little computing power in the control unit.

The present invention also discloses a charging system for inductively charging an electric vehicle, comprising an inductive link, a security area that penetrates and surrounds the inductive link, an apparatus for monitoring the security area of living objects with a controller and sensors, and means for providing the charging power, which is controlled by the device for monitoring the security area on living objects, wherein the device for monitoring the security area on living objects performs a method as described above.

In a preferred embodiment, the security object monitoring device includes an FSCW radar for living objects. This measure has the special advantage of the high information density of the FSCW radar, over which the state in the air gap of the inductive transmission line can be monitored very well.

In another embodiment, the device for monitoring the security area on living objects has a capacitive sensor path. Also, this type of sensor is well suited for monitoring, and offers the advantage of simpler and cheaper execution.

In another embodiment, the device for monitoring the security area on living objects on a Doppler radar. A Doppler radar is also suitable for monitoring and also has the advantage of a more cost-effective implementation by existing system components for the distance measurement of vehicles.

In another embodiment, the security object monitoring device includes a camera-based optical monitoring system for living objects. This sensor type can also claim the advantage of being cost-effective, since such systems are used in the driver assistance systems and can be adapted to the new task with manageable changes.

In a further preferred embodiment, the device for monitoring the security area on living objects switches off the charging power when the electric vehicle leaves the charging system. This advantageously increases the security of the charging system according to the invention, since high field strengths are prevented when not in use.

In another embodiment, the sensors of the device for monitoring the security area on living objects are at least two antennas, which are arranged such that they illuminate the security area. Due to the embodiment with at least 2 antennas, the security area can advantageously be extended and adapted in the form.

In another embodiment of the charging system, it is set up to measure the distance of a security object to each of the antennas in the steps of monitoring the security area for intruding objects and monitoring the security area for the presence of a living object within the security area, and to use a sensor fusion ambiguous or unique position of the object within the security area. Due to the advantageous use of multiple antennas and a sensor fusion, the position of the object within the security area can advantageously be determined precisely and simply.

In another preferred embodiment, the charging system is configured to arbitrarily shape the security area by means of the sensor fusion of the at least two antennas and thus to adapt the shape of the inductive transmission path. By means of the sensor fusion, an almost arbitrarily shaped region can advantageously be monitored via the distance measurement of individual antennas, and the monitored area can thus be advantageously adapted to the shape of the inductive transmission path.

Further advantageous developments and refinements of the charging system and charging method according to the invention will become apparent from further dependent claims and from the following description.

The above embodiments and developments can, if appropriate, combine with each other as desired. Further possible refinements, developments and implementations of the invention also include combinations of features of the invention which have not been explicitly mentioned above or described below with regard to the exemplary embodiments. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention.

Brief description of the drawings

Further advantages, features and details of the invention will become apparent from the following description of exemplary embodiments and with reference to the drawings, in which the same or functionally identical elements are provided with identical reference numerals.

Showing:

1 a schematic plan view of an inductive charging system electric vehicle in a first embodiment,

2 the schematic plan view 1 with the recorded surveillance area of one of the four radar antennas,

3 the schematic plan view of 2 with all four surveillance areas of the four radar antennas,

4 a flowchart of the method for monitoring an inductive transmission link of a first embodiment with a FSCW radar,

5 a distance distribution of the objects in the monitored area,

6 a range of motion of the prominent peaks of the distance distribution 5 .

7 the Fourier transform of the motion spectrum 6 .

8th a flowchart of the method for monitoring an inductive transmission path of a second embodiment with a capacitive measuring method,

9 a flowchart of the method for monitoring an inductive transmission link of a third embodiment with a Doppler radar,

10 a flowchart of the method for monitoring an inductive transmission path of a fourth embodiment with an optical camera-based measurement method.

Preferred embodiment of the invention

1 shows a schematic plan view of an inductive charging system 1 in a first embodiment. On the inductive charging system 1 is an electric vehicle 11 which is to be loaded.

The charging system has a loading area 5 on, about which the charging electric vehicle 11 is placed, and that together with the in the electric vehicle 11 built-in counterpart (not shown) an inductive transmission path 5 forms. To the cargo area or transmission line 5 There is a security area around 3 that of a device for monitoring the security area on living objects 8th is monitored. In the first embodiment, the security area monitoring apparatus uses living objects 8th a FSCW radar with corresponding antennas 9 , The abbreviation FSCW-Radar stands for "Frequency Stepped Contionous Wave Radar". This radar technology is known per se and is used in this embodiment according to the invention in two different detection modes to accomplish the monitoring of the security area of the transmission line can. The device for monitoring the security area on living objects 8th also has a control unit 7 on which with the antennas 9 connected is. In the FSCW system, the antennas 9 in the intermediate space, eg on the ground, near the ground, on the vehicle underbody or in vehicle underbody proximity. It uses ultra-wideband radio frequency signals from these antennas 9 be radiated or received, the space between the ground and the vehicle 11 supervised.

2 shows by way of example the footprint of one of these radar antennas 9 on the schematic representation of 1 , He is set to be the security guard 3 illuminates.

3 shows the schematic plan view of 2 with all four surveillance areas of the four radar antennas. The hatched areas show the footprint of all 4 Radar antennas. As long as the controller 7 the signals of at least 3 Radar antennas evaluates, it can determine by determining the distances to the object this unique in the footprint of the radar antennas (multilateration) and thus between an object inside and outside of this security area 3 to distinguish exactly. By a distance measurement of at least three radar antennas, a unique position of the object in the footprint of the radar antennas can be determined, whereby the security area 3 may have any shape, which may also differ from the footprint of the radar antennas. An object in the security area 3 is thus reliably detectable.

The surveillance of the security area 3 happens with a combination of two different detection modes of the FSCW radar for living object detection:
In the first mode, also referred to below as "intrusion detection", the focus is on fast and secure detection of any objects in the security area 3 directed. When the charging system is switched on, rapid and simultaneously classifying detection of penetrating objects takes place in order, if necessary, to be able to switch off the charging system as quickly as possible. The second mode, hereafter also referred to as "living object detection", is directed to sensitive detection of movement patterns such as breath or the pulse of living beings or spatial characteristics of living objects so that a living object can be safely distinguished from non-critical other objects. This mode is active when the inductive transmission link 5 is off.

The device for monitoring the security area on living objects 8th is thus able to start, perform or switch off or interrupt the inductive charging process. Depending on the safety requirements, the switch-on and switch-off actions can be faster or slower. By separating intrusion detection and living object detection, the advantageous use of such sensor systems as the FSCW radar of the first embodiment is possible, which can be set differently and at the same time provide a wealth of information. Thus, in case of doubt, a quick shutdown is guaranteed, as well as in the presence of a living object, the permanent deactivation. For the sophisticated distinction of living from other objects is thus a sufficient amount of time available.

4 shows a flowchart of the method for monitoring an inductive link of the first embodiment with the FSCW radar. The executing the method System knows two states, state 403 , "Charging allowed", ie "charge allowed", and state 405 , "Charging not allowed", ie "Charging not allowed".

If a vehicle drives onto the charging system, the system can start in one of the two modes. If the security requirements are high, the system starts in mode 405 , "Charge not allowed". Now, the security area monitoring device targets living objects 8th the second detection mode, and checked in step 404 the security area 3 on living objects. If no living object is detected, because the signal changes little or only randomly, then the system goes into the mode 403 , "Charging allowed".

Before, the boundary parameters in step 401 still adapted to the current situation, the system is "normalized", so to speak. In the mode 403 , "Charging allowed" works the device for monitoring the security area on living objects 8th in the first detection mode. Here is the security area in step 402 monitored for intrusion of any objects, and the transmission link 5 is switched off immediately as soon as an object classified as potentially critical is detected. Shutting down will cause the system to return to the mode 405 , "Charging not allowed" is located, and the device for monitoring the security area on living objects 8th works again in the second detection mode in step 404 ,

Switching on the charging process is triggered by a vehicle to be loaded, which is on the charging pad of the inductive transmission path 5 drives and activates the charging process. Sooner or before the start of the charging process, the device for monitoring the security area becomes live objects 8th activated and the space is monitored and a "virtual fence" placed around the area of high field intensity.

Switching off the charging process or temporarily switching off the charging process is in step 404 triggered by a potentially living object, which is detected in the space, or in the step 402 by a potentially living object which penetrates into the area to be monitored (virtual fence is penetrated), or the vehicle to be loaded drives away or is full.

In step 406 a detection of the restored zero state is checked within a predetermined time. The "zero state" identifies the state which was previously recognized as uncritical and stored in the system, optionally compensated for drift. If the system returns to the zero state, it can be assumed that the "disturbance" was only transient, and the system can tell about the states 401 and 403 be turned on again. However, if the zero state measurably not recovered, must in the step 404 to examine more closely whether the change in space is due to a living object. If no living object is detected here, then it becomes a step 401 jumped. Here the system is normalized, ie the zero state is set, and the system then goes back into the mode 403 , "Charging allowed".

The charging process is switched on again in step 406 also triggered by a recognition that the zero state is not reached, but the deviation in the detection range of a non-living object is due.

The continuous switching off of the charging process is carried out with recognition of patterns (movement, contour) of living objects in the step 404 ,

With this approach, the security area 3 be monitored safely.

The advantage of the ultra-wideband radar system (FSCW radar) of the first embodiment is that the high bandwidth gives a wealth of information that allows to conclude with high certainty on the system state with regard to zero state or penetrating objects. In particular, a distance distribution of an object can be determined with the principle of the "Frequency Stepped Continuous Wave" (FSCW) radar. Thus, the system will be advantageous for extended objects or for interferences, e.g. Regulated with water films, since these can be hidden as time-stable targets.

The device for monitoring the security area on living objects 8th is therefore mostly in the second mode in the step 404 able to detect small movements (eg breathing of an animal) of any object that is already in the safety area 3 (within a virtual fence, so to speak). In particular, the device for monitoring the security area on living objects 8th Regular movements such as pulse rate or breathing through observation over a period of a few tens of seconds to detect relatively stable, thus preventing a false reconnection of the inductive charging path. For this purpose, one over a few seconds, in the first embodiment according to the flowchart of the step 404 of the 4 15 seconds, recorded measurement signal of the FSCW radar from the frequency range (amplitude and phase shift as a function of frequency) for each time measurement step transformed by Fourier transformation in the time domain (amplitude and phase shift). An example of such Fourier transformed measurement is in 5 specified. 5 shows a distance distribution of the objects located in the monitored area. The time domain reflects the distance distribution of the target detected by the radar antenna. The distance distribution shows in which object distances movements have occurred:
Prominent Peaks 551 . 553 in the distance distribution, their temporal behavior is analyzed. For this purpose, all Fourier amplitudes are combined at the corresponding distance in a time series.

The composite time series of the measurement 5 is in 6 to see. 6 shows a range of motion of the prominent peaks of the distance distribution 5 ,

This time series is in turn Fourier transformed so that the motion spectrum arises at the corresponding distance. This movement spectrum is in 7 to see. 7 shows the Fourier transform of the motion spectrum 6

In the case of a periodic movement in the range of about 0.2 to 0.6 Hz can be concluded on a breathing movement. For this purpose, the motion spectrum is integrated in the corresponding frequency range and the integral compared with the noise level of the entire spectrum. Clearly visible is the increased amplitude in the black background area 7 at about 0.5 Hz. This is the measurement of breathing one in the safety area 3 located cat. The mean amplitude is in line 711 shown, the amplitude of the black area is the line 712 , Once a larger area the average amplitude 711 is exceeded, a living object should be assumed to be in a predetermined frequency range indicative of respiration or pulse.

The last evaluation step (Fourier analysis of a time series) is not limited to the first embodiment but may be applied to any other methods in which a time-dependent amplitude that correlates with the movement of the object is measured.

When FSCW radar is, however, if multiple antennas are used and arranged advantageously, also a localization of objects and thus a precisely limited detection range is possible. Furthermore, the distance distributions allow conclusions about the type of object. 8th shows a flowchart of the method for monitoring an inductive transmission path of a second embodiment with a capacitive measuring method. The second embodiment is similar to the first embodiment, therefore, only the differences from the first embodiment will be described.

The second embodiment uses a capacitive detection method instead of the FSCW radar. In this case, corresponding electrically conductive surfaces are attached to the charging station or to the vehicle, and the control unit 7 constantly measures the capacity between these two potentials. The conductive surfaces are preferably located next to one another on a plane, as a result of which objects which approach this plane at the level of the two surfaces can be well recognized. If something penetrates into the space near the two electrically conductive surfaces, the capacity of the arrangement changes and the object can be recognized by the change of the capacitance.

The load can again, depending on the safety requirement, in the step 802 or in the step 804 to be started. In case of high security requirements is in step 804 started.

For the capacitive method, the system checks in step 804 after deflection from hibernation by penetration of an object into the security area 3 to an unchanged or fast, random and weakly changing state in the security area 3 , From this it is concluded that no living object is in the air gap. Changes the state in the security area 3 Periodically in the frequency range of living beings (or their characteristic variables such as pulse) or find significant movements instead (eg arm or leg roams through), so the charging system remains off.

There is no living object in the security area 3 , the system changes to the state 803 , and the charge is activated. The method according to the invention now periodically carries out the steps 802 and 801 by. As long as no intrusive potentially living object in the security area 3 is detected, the system remains in the state 803 , "Charge Allowed" and the vehicle will go over the inductive link 5 loaded. Once in step 802 the penetration of a potentially living object into the security area 3 is detected, the system immediately goes into the state 805 , "Charge not allowed". The inductive transmission path 5 is switched off and in step 806 a check is made as to whether the system has again reached the previous zero state, possibly compensating for drift. If this is the case, it can be assumed that the "disturbance" was only temporary, and the system can use the states 801 and 803 be turned on again. However, if the zero state measurably not recovered, must in the step 804 to examine more closely whether the change in space is due to a living object. is If so, then the system jumps back to the state 805 "Charge not allowed". Only if no potentially living object in the security area 3 is detected more, the system goes back to the state 803 , "Charge allowed". Before that gets in step 801 again a "standardization" on the current conditions in the security area 3 performed to reset the zero state.

Also in the second embodiment, there is so in the step 801 an adaptation to the current conditions, before the device for monitoring the security area on living objects 8th the monitoring begins. The security area is thus "normalized" before the monitoring, as in the previous embodiment, so that changes can be better recognized.

After normalization, the load is thus released, and the device for monitoring the security area on living objects 8th is in the first mode in which step 802 only a short time range of 1s is considered to be able to detect any intrusion of any objects in the security area. If an object is detected, then the inductive transmission path 5 shut off, and the device for monitoring the security area on living objects 8th then works in the second mode to step by step living objects 804 in the security area 3 to be able to detect.

If no living object is detected, the charge is restarted after another "normalization".

9 shows a flowchart of the method for monitoring an inductive transmission path 5 a third embodiment with a Doppler radar. The third embodiment is similar to the first embodiment, therefore, only the differences from the first embodiment will be described.

The load can again, depending on the safety requirement, in the step 902 or in the step 904 to be started. In case of high security requirements is in step 904 started.

There is no living object in the security area 3 , the system changes to the state 903 , and the charge is activated. The method according to the invention now periodically carries out the steps 902 by. As long as no intrusive potentially living object in the security area 3 is detected, the system remains in the state 903 , "Charge Allowed" and the vehicle will go over the inductive link 5 loaded.

Once in step 902 the penetration of a potentially living object into the security area 3 is detected, the system immediately goes into the state 905 , "Charge not allowed". The inductive transmission path 5 is switched off and the step 904 is subsequently executed periodically, as long as a potentially living object in the security area 3 is detected. Only if no potentially living object in the security area 3 is detected more, the system goes back to the state 903 , "Charge allowed".

In the Doppler radar, the system persists due to the lack of opportunities to detect a statically altered gap in the state 905 "Charge not allowed" mode as soon as an object that has entered the gap is there and moves only slightly or not at all. A quick restart is not possible, as a restoration of a previous state can not be detected. This is a significant difference from the first embodiment because it is possible with an FSCW radar system. Only when it has been detected that no or only uncritical movements take place in the air gap, may it be switched on again.

10 shows a flowchart of the method for monitoring an inductive transmission link of a fourth embodiment with an optical camera-based measurement method. The fourth embodiment is similar to the first embodiment, therefore, only the differences from the first embodiment will be described. In the optical or thermo-optical method, the system checks whether there is something in the intermediate space that has the contour of a living being (or body part). The images delivered by the camera are thus checked for changes using evaluation algorithms, and structures that represent the contour of a living being are recognized. In this case, no charge may take place. On the other hand, if the state in the intermediate space changes with rapid, random movements or not at all, charging will take place. Motion detection of complex motion patterns can also be used to detect living objects and reduce false alarms.

The load can again, depending on the safety requirement, in the step 1002 or in the step 1004 to be started. In case of high security requirements is in step 1004 started.

There is no living object in the security area 3 , the system changes to the state 1003 , and the charge is activated. The method according to the invention now periodically carries out the steps 1002 by. As long as no intrusive potentially living object in the security area 3 is detected, the system remains in the state 1003 , "Charge Allowed" and the vehicle will go over the inductive link 5 loaded.

Once in step 1002 the penetration of a potentially living object into the security area 3 is detected, the system immediately goes into the state 1005 , "Charge not allowed". The inductive transmission path 5 is switched off and the step 1006 will be executed periodically until the previously stored zero state is approximately reached again. If this is the case, the system returns to the state 1001 to perform a new normalization and new definition of zero state, and to start the charge again. Here it can be assumed that the "disturbance" was only temporary.

However, if the zero state is measurably not recovered, the step becomes 1004 executed and tested whether a potentially living object in the security area 3 is detected. Only if no potentially living object in the security area 3 is detected more, the system goes back to the state 1003 , "Charge allowed". Before that gets in step 1001 again a "standardization" on the current conditions in the security area 3 carried out. Becomes a living object in the security area 3 detected, the system remains in state for so long 1005 , "Charge not allowed" until the zero state is at least approximately reached again.

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

• US 2008/0103660 A1 [0005]
• WO 01/17838 A1 [0006]

Claims (15)

Method for monitoring an inductive transmission link ( 5 ) to living objects, comprising an inductive transmission link ( 5 ) and a locally the inductive transmission link ( 5 ) penetrating and surrounding security area ( 3 ), with the following steps: when the inductive transmission path ( 5 ) Surveillance of the security area ( 3 ) on penetrating objects and switching off the inductive transmission link ( 5 ) upon detection of an intruding object in the security area ( 3 ); when the inductive transmission path is switched off ( 5 ) Surveillance of the security area ( 3 ) on the stay of a living object within the security area ( 3 ) and blocking the inductive transmission link ( 5 ) upon detection of a living object within the security area ( 3 ). Method according to claim 1, characterized in that an electric charging power for an electric vehicle ( 11 ) via the inductive transmission path ( 5 ) is transmitted. Method according to claim 1 or 2, characterized in that the inductive transmission path ( 5 ) is turned on again when it is detected that no living object in the security area ( 3 ) stops. Method according to one of the preceding claims, characterized in that when monitoring the security area ( 3 ) on penetrating objects a time range of 0 s to 5 s is measured. Method according to one of the preceding claims 1 to 3, characterized in that when monitoring the security area ( 3 ) on the stay of a living object within the security area ( 3 ) a time range of 5 s to 30 s is measured. Method according to one of the preceding claims, characterized in that the corresponding measurements are analyzed based on object distances or maxima of the object distance distribution, time series are composed of the object distances or maxima of the object distance distribution of a plurality of successive measurements, these are Fourier-transformed and analyzed for frequencies on to indicate a living object. A method according to claim 6, characterized in that the frequencies indicative of a living object are frequencies of respiration, of the pulse or characteristic movements of the living object. Charging system ( 1 ) for inductive charging of an electric vehicle ( 11 ), comprising: an inductive transmission link ( 5 ); a security area ( 3 ), which the inductive transmission path ( 5 ) penetrates and surrounds locally; a device for monitoring the security area for living objects ( 8th ) with a control device ( 7 ) and sensors ( 9 ); means for providing the charging power supplied by the security surveillance device to living objects ( 8th ) is controlled; the security surveillance device being based on living objects ( 8th ) is configured to carry out a method according to one of claims 1 to 8. Charging system according to claim 8, characterized in that the device for monitoring the security area is based on living objects ( 8th ) has an FSCW radar. Charging system according to claim 8, characterized in that the device for monitoring the security area is based on living objects ( 8th ) has a capacitive sensor path. Charging system according to claim 8, characterized in that the device for monitoring the security area is based on living objects ( 8th ) has a Doppler radar. Charging system according to claim 8, characterized in that the device for monitoring the security area is based on living objects ( 8th ) has a camera-based optical monitoring system. Charging system according to one of claims 9 or 11, characterized in that the sensors ( 9 ) are at least 2 antennas, which are arranged so that they illuminate the security area. Charging system according to claim 13, characterized in that it is arranged in the steps monitoring the security area ( 3 ) on intruding objects and surveillance of the security area ( 3 ) to measure the distance of an object located in the security area to each of the antennas and to combine it by means of sensor fusion into an ambiguous or unique position of the object within the security area on the stay of a living object within the security area. Loading system according to claim 14, characterized in that it is set up, the security area ( 3 ) by means of the sensor fusion of at least two antennas to form arbitrarily and thus the shape of the inductive transmission path ( 5 ).

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