Method and device for detecting living body for inductive charging device

Abstract

The present invention relates to a device and method for detecting a living body used in an inductive charging device, wherein the inductive charging device (101) has a resonator coil (1) configured to generate an electromagnetic field and has a plurality of living body sensors (2) configured to detect a living body. The method has the following steps: determining a critical magnetic field limit (3) of an electromagnetic field by using a magnetic field limit sensor (4), wherein the critical magnetic field limit (3) is defined as a magnetic field intensity outside the critical magnetic field limit (3) being lower than a limit value; and detecting a living body within the determined critical magnetic field limit (3) of the electromagnetic field by using the living body sensor (2).

Description

Technical Field

[0001] The present invention relates to a method and a device for detecting a living body used in an inductive charging device. Background Art

[0002] A conventional inductive charging device as a device for power transmission has a basic module, a vehicle module and a wall box. The wall box attached to the wall feeds the input alternating current into the transmitting coil located in the basic module via a high-voltage line, thereby generating an electromagnetic field. A portion of the energy of the electromagnetic field generated in the transmitting coil is transmitted to the receiving coil located in the vehicle module, which in turn generates an electromagnetic field with a corresponding output alternating current. The transmitting coil and the receiving coil are called resonator coils, which are arranged in a so-called resonator. A rectifier is arranged in the vehicle, which rectifies the output alternating current and feeds it to a DC voltage charging device for charging the vehicle battery.

[0003] The energy transmitted electromagnetically during inductive charging of electric or hybrid vehicles has values ​​of the order of magnitude of, for example, 85 kHz and 11 kW. The high transmission power in the air gap generates strong electromagnetic alternating fields (several mT), which are potentially harmful to health (including carcinogenicity and harmful to fertility). For this reason, the radiation to humans is limited when used for inductive charging to 6.25 μT, for example in the ICNIRP 1998 standard (Table 7).

[0004] Therefore, the space around the vehicle or under the vehicle must be monitored in which this limit value is exceeded and a reaction must be triggered, such as reducing or switching off the transmission power. The monitoring usually has to take place under the vehicle contour. For this purpose, groups of HF sensor modules can be attached to the basic module, with the help of which the area under the vehicle and areas outside the vehicle underbody can be monitored.

[0005] The underbody of a vehicle presents extreme challenges for radar sensors due to complex reflection problems and a high backscatter cross section. In addition, due to the various applications, significant environmental influences must also be taken into account (snow, ice, rain, various coverings such as wet leaves, etc.). In addition, living objects that can be reliably detected usually have a very small radar signature and may move very slowly (e.g. a sleeping cat). On the other hand, regulatory specifications and customer requirements that require rapid shutdown or power reduction of energy transmission systems in the event of an accident must be met.

[0006] The peripheral area around the base plate of the energy transmission system up to the outer edge of the vehicle floor and beyond this outer edge presents a particular challenge, on the one hand to ensure reliable detection of living bodies and on the other hand to keep the number of false detections limited. Therefore, there are high requirements on the selectivity of the peripheral area and the adaptability to the specific situation. An added difficulty is that the geometry of the detection area is highly variable. While small charging power levels, good vehicle positioning and low vehicle height produce relatively compact and symmetrical magnetic fields, high charging power levels, poor positioning and large ground clearance can lead to significantly increased asymmetric limitations.

[0007] As part of the development of inductive charging devices, solutions were sought to reliably detect living bodies in the area of ​​the magnetic field of the base unit, but not to react to objects located outside this area. One approach is to detect moving objects with high-frequency sensors. Due to possible user specifications, it may be necessary to install the sensors for air gap monitoring (vehicle underbody and defined adjacent areas) completely in the substrate of the energy transmission system. An added difficulty is that the sensors must operate reliably when transmitting energy, with corresponding requirements for robustness and interference immunity. There are high requirements for selectivity in the surrounding area and adaptability to specific situations (e.g. transmission power, underbody height, vehicle type, etc.). Summary of the invention

[0008] The present invention is based on the object of providing a method and a device for detecting living organisms for an inductive charging device, which shut down the inductive charging device as infrequently as possible but as often as possible due to the detection of living organisms.

[0009] This object is achieved by the subject matter according to the invention. Advantageous embodiments of the invention are described in the dependent claims.

[0010] A first aspect of the present invention relates to a method for detecting a living body for an inductive charging device, the inductive charging device having a resonator coil configured to generate an electromagnetic field and a plurality of living body sensors configured to detect a living body. The method has the following steps: determining a critical magnetic field limit of an electromagnetic field by a magnetic field limit sensor, the critical magnetic field limit being defined as a magnetic field intensity outside the critical magnetic field limit falling below a limit value; and detecting a living body within the determined critical magnetic field limit of the electromagnetic field by the living body sensor.

[0011] The real-time or online determination of the actually existing critical magnetic field limits enables an increased selectivity to be displayed in the detection of living organisms. The net effect of the process is that the power transmission to the resonator coil is only switched off when it is actually required by the living organism. The transmitted energy is thus maximized, so that, for example, a high vehicle range can be achieved.

[0012] The method preferably also includes the step of using a three-dimensional magnetic field model in the step of determining the critical magnetic field limit. The magnetic field model is preformed, more preferably offline, by a step for recording the three-dimensional coordinates of the critical magnetic field limit under various operating conditions by means of an external magnetic field detector and taking into account the determined values ​​recorded by the magnetic field limit sensor. The various operating conditions can be the transmission power, the alignment of the vehicle with the basic module or the height distance between the vehicle and the basic module. When the three-dimensional coordinates of the critical magnetic field limit under various operating conditions are recorded by means of an external magnetic field detector and using the determined values ​​from the magnetic field limit sensor, the three-dimensional coordinates of the critical magnetic field limit are obtained.

[0013] The method preferably further comprises the following steps: determining at least one geometric entity, which is defined by at least one geometric parameter and encompasses the recorded three-dimensional coordinates of the critical magnetic field limit; and determining a magnetic field model as a function of at least one geometric parameter of the entity based on the various values ​​recorded by the magnetic field limit sensor. The geometric entity may be an ellipsoid, a cylinder or a sphere.

[0014] The method preferably further comprises the following steps: segmenting the recorded three-dimensional critical magnetic field limit by means of various geometric entities, each of which is determined by at least one geometric parameter and surrounds the recorded three-dimensional coordinates of the critical magnetic field limit; and determining a magnetic field model as a function of the geometric parameters of the various entities from the various values ​​recorded by the magnetic field limit sensor. The geometric parameters may be the length, width, height, angle, radius or volume of the geometric entity.

[0015] Preferably, the magnetic field model is pre-stored in a memory of a control unit of the inductive charging device and is retrieved during the step for determining the critical magnetic field limit or is made available via a network (online).

[0016] A second aspect of the present invention relates to a device for detecting a living body used in an inductive charging device, the inductive charging device having a resonator coil configured to generate an electromagnetic field and a plurality of living body sensors configured to detect a living body. The device has a magnetic field limit sensor for determining a critical magnetic field limit of the electromagnetic field, the critical magnetic field limit being defined as a magnetic field intensity outside the critical magnetic field limit falling below a limit value. The device also has a living body sensor for detecting a living body within the determined critical magnetic field limit of the electromagnetic field.

[0017] In a plan view of the resonator coil, the magnetic field limit sensor is preferably arranged radially between the resonator coil and the living body sensor.

[0018] Preferably, the magnetic field limit sensor is an (inductive) coil and / or the live body sensor is a radar sensor.

[0019] Preferably, the resonator coil, the living body sensor and the magnetic field limit sensor are integrated in the resonator module, so that a compact arrangement is formed.

[0020] Preferably, the inductive charging device is configured to charge an electric vehicle used to transport people or loads.

[0021] It should be noted that embodiments of the invention have been described with reference to different subject matters of the invention. In particular, some embodiments of the invention are described by method claims and other embodiments of the invention are described by apparatus claims. However, it will be immediately clear to a person skilled in the art upon reading this application that, unless expressly stated otherwise, any combination of features associated with different types of subject matters of the invention in addition to combinations of features associated with one type of subject matter of the invention is also possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Further advantages and features of the invention are apparent from the following description of preferred embodiments given by way of example.

[0023] Figure 1 Schematically illustrates a device for energy transmission according to an exemplary embodiment of the present invention;

[0024] Figure 2 schematically shows a plan view of an inductive charging device;

[0025] Figure 3 Schematically shows a plan view of an inductive charging device, showing three different critical magnetic field limits at three different locations of the vehicle above a basic module;

[0026] Figure 4 A schematic diagram of a plan view of an inductive charging device is shown, showing three different critical magnetic field limits at three different magnetic field strengths;

[0027] Figure 5 Schematically shows a plan view of an inductive charging device, showing three different critical magnetic field limits at three different height distances between the vehicle floor and the basic module;

[0028] Figure 6 Four different exemplary embodiments of the arrangement of magnetic field limit sensors in a basic module are shown;

[0029] Figure 7 A flow chart illustrating a method of using a magnetic field model according to an exemplary embodiment; and

[0030] Figure 8 Schematically shows the Figure 7 The method is based on the segmentation of the recorded three-dimensional critical magnetic field boundaries by various geometric entities. DETAILED DESCRIPTION

[0031] It should be noted that the exemplary embodiments described below are only a limited selection of possible variant embodiments of the present invention.

[0032] Figure 1 A device for energy transmission according to an exemplary embodiment of the present invention is schematically shown in the form of an inductive charging device for an electric vehicle for transporting people or loads. The inductive charging device has a basic module 101, a vehicle module 102 and a wall box 105. The wall box 105 attached to the wall feeds the input alternating current to the resonator coil (transmitting coil) located in the basic module 101 via a high-voltage line 106, and the resonator coil (transmitting coil) thereby generates an electromagnetic field. Part of the energy of the electromagnetic field generated in the transmitting coil is transmitted to the resonator coil (receiving coil) located in the vehicle module 102, whereby the resonator coil (receiving coil) in turn generates an electromagnetic field with a corresponding output alternating current. A rectifier is arranged in the vehicle, which rectifies the output alternating current and feeds it to a DC voltage charging device for charging the vehicle battery.

[0033] The transmitting coil and the receiving coil are each referred to as resonator coils and are arranged in corresponding resonators 103, 104 of the base module 101 and the vehicle module 102. The resonator coils each form a current-carrying wire, which is usually formed of a litz wire.

[0034] Figure 2 A plan view of an inductive charging device in the form of a base module 101 is schematically shown. A live body sensor 2 in the form of a radar sensor is installed in each of the four corners of the base module 101. Reference numeral 9 denotes a vehicle profile of a vehicle parked above the base module 101 for charging. Reference numeral 3 denotes a critical magnetic field limit of the electromagnetic field generated by the resonator coil. The critical magnetic field limit 3 is defined as the magnetic field strength outside the critical magnetic field limit 3 falling below a predetermined limit value.

[0035] However, the critical magnetic field limit 3 does not have a constant shape and size, but varies significantly in some cases depending on the prevailing operating conditions.

[0036] Figure 3 The schematic diagram of the inductive charging device shows three different critical magnetic field limits 3 at three different locations of the vehicle above the base module 101. Poor positioning of the vehicle often leads to distorted and enlarged critical magnetic field limits 3.

[0037] Figure 4The schematic diagram of an inductive charging device shows a plan view of three different critical magnetic field limits 3 with three different magnetic field strengths. An increase in the charging power generally also leads to an increased critical magnetic field limit 3 .

[0038] Figure 5 The schematic plan view of the inductive charging device shows three different critical magnetic field limits 3 at three different height distances between the vehicle floor and the basic module 101. Conversely, a low vehicle will result in a reduction of the critical magnetic field limit 3 in most cases.

[0039] Therefore, a living body located at a certain point may sometimes be within the critical magnetic field limit 3 and sometimes outside it. Without knowing the current, the critical magnetic field limit 3, the only feasible option is to interrupt the power transmission to turn off the magnetic field. The result will be that the battery is not fully charged and the vehicle's mileage is reduced. Therefore, it is desirable to determine the current critical magnetic field limit 3 in order to ensure maximum power transmission.

[0040] The concept presented below is based on the combination of sensor signals of several living body sensors 2 with an additional magnetic field limit sensor 4 for determining the local magnetic field strength or for measuring the magnetic field.

[0041] Figure 6 Four different exemplary embodiments of the arrangement of magnetic field limit sensors 4 in a basic module 101 are shown. All sensors 2 , 4 are integrated in the basic module 101 .

[0042] The magnetic field limit sensors 4 preferably operate according to the inductive principle and they can be designed as simple and therefore cheap coils with one or more turns. Their number, size, shape and arrangement should be made suitable for the topology of the system under consideration.

[0043] exist Figure 6 In the upper left image and the lower left image in FIG, an exemplary embodiment of a circular primary coil concept is shown. Figure 6 In the image at the upper left of , a plurality of (for example six) magnetic field limit sensors 4 are arranged radially outside the resonator coil 1 in a rotationally and mirror-symmetrical manner. In addition, a central magnetic field limit sensor 4 is arranged in the center of the resonator coil 1. In a plan view of the resonator coil 1, the six external magnetic field limit sensors 4 are arranged radially between the resonator coil 1 and the live body sensors 2, one of which is located in each of the four corners of the basic module 101. Figure 6In the image at the bottom left of FIG. 1 , a plurality of (e.g., four) magnetic field limit sensors 4 are radially arranged in a rotationally and mirror-symmetrical manner inside the resonator coil 1. In a plan view of the resonator coil 1, the resonator coil 1 is radially arranged between the magnetic field limit sensors 4 and the living body sensors 2, one of which is located in each of the four corners of the basic module 101.

[0044] exist Figure 6 In the upper right image and the lower right image of FIG, an exemplary embodiment of a rectangular primary coil concept is shown. Figure 6 In the image at the upper right of , a plurality of (for example six) magnetic field limit sensors 4 are arranged radially outside the resonator coil 1 in a rotationally and mirror-symmetrical manner. In addition, a central magnetic field limit sensor 4 is arranged in the center of the resonator coil 1. In a plan view of the resonator coil 1, the six outer magnetic field limit sensors 4 are arranged radially between the resonator coil 1 and the live body sensors 2, one of which is located in each of the four corners of the basic module 101. Figure 6 In the image at the bottom right of FIG. 1 , a plurality of, for example four, magnetic field limit sensors 4 are arranged radially in a rotationally and mirror-symmetrical manner inside the resonator coil 1. In a plan view of the resonator coil 1, the resonator coil 1 is arranged radially between the magnetic field limit sensors 4 and the live body sensors 2, one of which is located in each of the four corners of the basic module 101. The coil axes of the four magnetic field limit sensors 4 are in each case substantially parallel to the corresponding side of the rectangular resonator coil 1.

[0045] In an exemplary embodiment, the number and arrangement of the living body sensors 2 and the magnetic field limit sensors 4 may be optimized in a coupled manner.

[0046] The signal of the inductive magnetic field limit sensor 4 represents a sinusoidal signal in a first approximation, whose frequency is equal to the frequency of the main magnetic field. The amplitude of this signal is proportional to the average local magnetic field strength. If flat (two-dimensional) coils are used, they can only measure orthogonal magnetic field components. However, the defined limit values ​​are based on effective values ​​that include all three spatial directions. There are several possible ways to avoid this problem:

[0047] - Modeling of one-dimensional measurements and their correlation transformation into three-dimensional effective values;

[0048] - More complex coil geometries, such as a cube with three mutually orthogonal coils;

[0049] - The different individual coils are tilted towards each other.

[0050] The system should be able to determine not only local magnetic field values, but also to infer values ​​far beyond the physical limits of the base module 101 (see Figure 2 and Figures 3 to 5 ). Modeling is therefore useful. A comprehensive determination of the three-dimensional critical magnetic field limit 3 under all relevant operating conditions can be the basis for modeling.

[0051] Reference below Figure 7 The exemplary embodiment of the present invention describes a method for detecting a living body for an inductive charging device, wherein Figure 7 In the case of the exemplary embodiment of , which comprises steps S1 to S5, a magnetic field model 5 is used. The magnetic field model 5 is predetermined in steps S1 to S3, ie determined offline in a region 7 of an offline analysis.

[0052] In step S1, firstly the three-dimensional coordinates of the critical magnetic field limit 3 are recorded under various operating conditions by means of an external magnetic field detector (not shown) and taking into account the specific values ​​recorded by the magnetic field limit sensor 4. The various operating conditions may be various charging power levels, various alignments and / or positions of the vehicle above the base module 101, various height distances of the vehicle above the base module 101, etc. In this regard, reference may be made to the three-dimensional coordinates of the critical magnetic field limit 3 under various operating conditions. Figures 3 to 5 The operating state explained in . An external magnetic field detector (not shown) is positioned so that it measures precisely at the current critical magnetic field limit 3, thereby indirectly establishing its 3D coordinates. As a result, in step S1, a complex 3D surface of the critical magnetic field limit 3 is obtained for the corresponding operating state.

[0053] In case measurement data is available, modeling can be performed. In step S2, at least one geometric entity is determined, which is defined by at least one geometric parameter x and surrounds the recorded three-dimensional coordinate of critical magnetic field limit 3. The geometric entity can be, for example, an ellipsoid, a cylinder or a sphere, and the geometric parameter x can be a radius, a bottom area, a volume and / or an axial length of an ellipsoid, a cylinder or a sphere. The geometric entity is selected to make it surround the recorded three-dimensional coordinate of critical magnetic field limit 3 on the one hand, but it is as little as possible on the other hand. Therefore, the geometric entity 6 can be similar to the critical magnetic field limit 3 by an approximation method.

[0054] In step S3, the magnetic field model 5 is determined as a function f of at least one geometric parameter x of the entity 6 from the various values ​​recorded by the magnetic field limit sensor 4, applying the following equation:

[0055] x=f (detection value of the magnetic field limit sensor 4).

[0056] In step S4 , the critical magnetic field limit 3 of the electromagnetic field is finally determined using the magnetic field model 5 determined in this way and the actual measured values ​​of the magnetic field limit sensor 4 .

[0057] In step S5, the living body sensor 2 then detects whether a living body is present within the determined critical magnetic field limit 3 of the electromagnetic field. If the living body sensor 2 detects a living body within the specific critical magnetic field limit 3 of the electromagnetic field, the resonator coil 1 can be switched off or its power can be reduced.

[0058] In contrast to steps S1 to S3 , steps S4 and S5 are performed online, ie in area 8 of an online application.

[0059] Figure 8 Schematically shows the Figure 7 The method case consists of a segmentation of the recorded three-dimensional critical magnetic field limits 3 by six different geometric entities. Figure 8 As an example, a segmented cylinder is shown together with hypothetical measurement data.

[0060] This variation of modeling is to segment or divide the 3D space into individual adjacent segments 6i, where i = 1..n, which represent simple geometric shapes. The individual parameters x of these shapes are then i (length, width, height, angle, radius, volume) can be described as a function of the signal of the internal magnetic field limit sensor 4 (see Figure 7 , Box 2 and Box 3). In this exemplary embodiment, the defined overall shape of all adjacent segments 6i also always represents the envelope of the three-dimensional measurement points for a specific operating state. The following equation applies:

[0061] x i =f (detection value of the magnetic field limit sensor 4).

[0062] If the magnetic field model 5 is not used at all or is already present, steps S1 to S3 in the area 7 of the offline analysis can also be omitted. If the magnetic field model 5 is not used, the critical magnetic field limit 3 of the electromagnetic field can also be recorded directly by the magnetic field limit sensor 4, for example only in the area 8 of the online application.

[0063] Magnetic field model 5 may be stored in advance in a memory of a control unit of inductive charging device 101 and retrieved during the step for determining critical magnetic field limit 3 , or it may be made available via a network, ie available online.

[0064] The transfer function of the internal magnetic field measurement to the critical magnetic field limit 3 can then be implemented on the control unit so that it can be evaluated during operation (online). The result of this evaluation is then correlated with the signal of the live main sensor system (live sensor 2) in order to make a final decision (switch off the magnetic field yes / no).

[0065] The living body sensor 2 (radar sensor) should be able to determine the position of the living body. Various options are available. For example, a frequency modulated system (FMCW) can directly determine the distance to the sensor. A constant frequency (CW) system does not have this capability; however, by using multiple CW sensors, the position of the living body can be indirectly inferred by evaluating the individual signal strengths.

[0066] The connection of the internal magnetic field limit sensor 4 and the living body sensor 2 (living body main sensor system) is not limited to the combination of induction coil and radar sensor. A combination of magnetic field measurement based on the Hall effect and a living body sensor system based on a camera would also be conceivable.

[0067] The net effect of the described process is that power transmission is only switched off when it is really necessary due to the detection of a living being. In other words: selectivity is increased.

[0068] Possible applications are all areas in which strong magnetic fields can be generated and at the same time living beings can access them, for example in production halls, power plants, induction cookers, magnetically operated loudspeakers or transformer substations.

Claims

1. A method for detecting a living body for an inductive charging device, wherein: The inductive charging device (101) has a resonator coil (1) configured to generate an electromagnetic field and a plurality of living body sensors (2) configured to detect living bodies, and the method has the following steps: Determining a critical magnetic field limit (3) of the electromagnetic field by means of a magnetic field limit sensor (4), wherein the critical magnetic field limit (3) is defined as the point at which the magnetic field strength outside the critical magnetic field limit (3) drops below a limit value; and Detecting a living body within the determined critical magnetic field limit (3) of the electromagnetic field by the living body sensor (2) also includes the following steps: A three-dimensional magnetic field model (5) is used in the step for determining the critical magnetic field limit (3), wherein the magnetic field model (5) is preformed by the following steps: recording the three-dimensional coordinates of the critical magnetic field limits under various operating conditions by means of an external magnetic field detector and taking into account the determined values ​​recorded by the magnetic field limit sensor (4), The following steps are also included: The recorded three-dimensional critical magnetic field limits are segmented by various geometric entities, each of which is determined by at least one geometric parameter (x i ) determining and enclosing the recorded three-dimensional coordinates of said critical magnetic field limits; and According to the various values ​​recorded by the magnetic field limit sensor (4), the magnetic field model (5) is determined as the geometric parameters (x i )’s function (f).

2. The method according to claim 1, The magnetic field model (5) is pre-stored in a memory of a control unit of the inductive charging device (101) and is retrieved during the step for determining the critical magnetic field limit (3), or it is made available via a network.

3. A device for detecting a living body for an inductive charging device (101), the inductive charging device (101) having a resonator coil (1) configured to generate an electromagnetic field and a plurality of living body sensors (2) configured to detect a living body using the following components: a magnetic field limit sensor (4) for determining a critical magnetic field limit (3) of the electromagnetic field, the critical magnetic field limit (3) being defined as the point at which the magnetic field strength outside the critical magnetic field limit (3) falls below a limit value; and The living body sensor (2) is used to detect a living body within a determined critical magnetic field limit (3) of the electromagnetic field, wherein: The device for detecting living bodies for an inductive charging device (101) is configured to implement the method according to claim 1 or 2.

4. The device according to claim 3, wherein: In a plan view of the resonator coil (1), the magnetic field limit sensor (4) is arranged radially between the resonator coil (1) and the living body sensor (2).

5. The device according to any one of claims 3 and 4, wherein: The magnetic field limit sensor (4) is a coil and / or the living body sensor (2) is a radar sensor.

6. The device according to any one of claims 3 and 4, wherein: The resonator coil (1), the living body sensor (2) and the magnetic field limit sensor (4) are integrated in a resonator module.

7. The device according to any one of claims 3 and 4, in, The inductive charging device (101) is configured to charge an electric vehicle used for transporting people or loads.

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