DE102013215034B4 - Charging device and method for inductive charging, in particular of electric vehicles - Google Patents

Abstract

Charging device for inductive charging, in particular of an electric vehicle (EV), comprising a charging coil (LS) for inductive charging and an object detector (5), the object detector (5) having a body with at least one dielectric region (10) with a flat side ( 20), at least one wave source (50) feeding the dielectric region (10) with electromagnetic waves (55), as well as a detection device for detecting at least one variable dependent on the propagation of the electromagnetic waves in the dielectric region (10) and an evaluation device, wherein the evaluation device is designed to infer the presence and/or the position, at least along the flat side, of an object on and/or near the flat side (20) as a function of this at least one variable, the dielectric region (10) being at least partially surrounded by an absorber material.

Description

In electric vehicles with chargeable electrical energy stores, such as chargeable electric batteries, the energy store must be supplied with the required energy regularly by charging. The importance of charging concepts in which the energy stores are charged without contact, in particular by inductive charging, is currently growing in importance.

With inductive charging, a coil embedded in the floor of a charging station generates an alternating magnetic field as a primary coil, which is received by a receiver coil installed on the underside of the respective electric vehicle as a secondary coil and converted into electrical charging current.

With inductive charging, there is typically an air gap between the charging coil of the charging station and the charging coil of the electric vehicle, across which high power is transmitted by means of the inductive charging field.

Metallic foreign bodies in the air gap can heat up during inductive charging due to eddy currents generated in the metal and cause fires. Furthermore, during inductive charging, biological tissue that gets into the air gap, such as human body parts or animals that get into the air gap, can be affected.

This circumstance is particularly dangerous if, for example as a result of medical treatment, there are metal parts in the body, in particular nails, screws or splints, which can also become very hot. Metal collars on animals, for example, are similarly problematic.

It is therefore necessary to detect objects such as foreign bodies in the air gap during inductive charging.

Plates with electrical structures are known, with which such a detection can in principle take place. For example, flat surfaces can be provided with buttons that are pressed in the direction of the flat surface by an object and then actuate an electrical switch. In this way, the presence and location of an object can be determined. Signals from a large number of keys or from all keys are transmitted to an evaluation unit via lines.

Furthermore, touch screens are known which are based on a capacitive, resistive or inductive operating principle: in touch screens the location of the object is often determined in such a way that a current flows along edges of the touch screen through a specific line whose location is known. Depending on the resolution, several lines must be connected along the edges of the touchscreen and the plate must be provided with structures that conduct electricity.

However, the electrical contacting that is always required is problematic with inductive charging systems, since wires and cables can be heated up by eddy currents during inductive charging, high voltages can be induced by conductor loops and/or the fields of the charging coil could be influenced in such a way that the energy efficiency of inductive charging could be affected store is reduced.

There are also attempts to provide active sensors, such as ultrasonic sensors or infrared sensors, for monitoring an air gap during inductive charging. However, these approaches are susceptible to failures due to contamination or destruction, have high cross-sensitivities or are not sufficiently accurate and therefore do not offer the reliability and robustness required in practice.

From the US2012/0049650A1 a device for inductive charging is known, which is designed for charging mobile devices such as mobile phones and notebooks. Also from the EN102012105615A1 a device for inductive, non-contact energy transmission is known, in which case energy can be transmitted to a secondary coil arrangement on a vehicle by means of a primary coil arrangement of a charging device. From the DE 102006038140A1 Finally, a detection device is known which allows the detection of vehicle occupants in a vehicle by means of a transmitting device, a receiving device and an evaluation device.

It is therefore the object of the invention to specify an improved charging device and an improved method for inductive charging, in particular of electric vehicles, with which an air gap can be monitored during charging reliably, robustly and in particular not susceptible to contamination.

This object is achieved with a charging device having the features specified in claim 1 and with a method for inductive charging, in particular of an electric vehicle, having the features specified in claim 11. Preferred developments of the invention are in the associated subclaims, the following description and the drawing.

The charging device according to the invention has a charging coil for inductive charging. Furthermore, the loading device according to the invention comprises an object detector. The object detector of the charging device according to the invention has a body with at least one dielectric area with a flat side that extends over an area. In addition, the object detector has a wave source, in particular a microwave source, that feeds the dielectric area with electromagnetic waves, in particular microwaves, as well as at least one detection device for detecting at least one variable dependent on the propagation of the electromagnetic waves in the dielectric area and an evaluation device, which is designed , as a function of this at least one variable, to infer the presence and/or the position, at least along the flat side, of an object on and/or near the flat side.

The phrase “close to the flat side” in the sense of this application is preferably to be understood as “at a distance of at most 10 wavelengths of the electromagnetic waves in the vacuum from the flat side”. In particular, under the phrase "with a distance of at most three wavelengths of the electromagnetic waves in a vacuum from the flat side", preferably "with a distance of at most one wavelength of the electromagnetic waves in a vacuum from the flat side" and ideally "with a distance of at most one half wavelength of the electromagnetic waves in vacuum from the flat side”.

In the case of the object detector of the charging device according to the invention, the electromagnetic waves propagating in the dielectric area take on the function of scanning the dielectric area along the flat side. In this way, in the case of the object detector of the charging device according to the invention, extensive wiring of the flat side extending over a surface area is not required. In particular, flat sides, the area of which clearly exceeds the currently usual size of touchscreens, can consequently be easily realized with the object detector according to the invention.

According to the invention, wires and cables can be dispensed with in the object detector of the charging device according to the invention. Consequently, the magnetic field of the charging coil and the components of the object detector do not adversely affect each other.

In addition, in the charging device according to the invention, the object detector is robust, in particular can be driven over by vehicles, and is insensitive to dirt and other external influences. Consequently, the object detector of the charging device according to the invention can be used to monitor an air gap during inductive charging in a reliable and robust manner with regard to contamination.

According to the invention, in the object detector of the charging device according to the invention, the dielectric area is at least partially surrounded by an absorber material. This effectively prevents standing electromagnetic waves from forming in the dielectric area. Standing electromagnetic waves in the dielectric area lead to areas on the flat side where the field strength of the electromagnetic waves disappears. The object detector would therefore hardly be sensitive at or near these points on the flat side. By contrast, the electromagnetic waves can be efficiently dissipated from the dielectric region by means of the absorber material, so that standing electromagnetic waves cannot form. The sensitivity of the object detector is consequently significantly improved in this development.

In the case of the object detector of the charging device according to the invention, the wave source is preferably designed as a microwave source and thus for feeding the dielectric region with microwaves. The microwave source suitably comprises a microwave transmitter which is connected to a coupling which is designed to couple the microwaves radiated by the microwave transmitter into the dielectric area, in particular by means of a waveguide feed and/or by means of coupling pins and/or by means of slot couplings.

In the case of the object detector of the loading device according to the invention, the body is expediently a flat part, in particular a plate, or has a flat part, in particular a plate. The dielectric area is particularly preferably in the form of a flat part, in particular a plate. Structures that are similar to conventional touch screens in terms of handling can thus be easily implemented. At the same time, the size of the object detector, as already explained above, is advantageously extremely freely scalable in this development of the invention.

In a preferred development of the invention, the body in the object detector has a layer structure, in particular with a dielectric layer with the flat side. Materials, thicknesses and sequences of the layers of the layered structure are expediently selected in such a way that the electromagnetic waves, esp particular guidance of microwaves within the body is optimized.

In the case of the object detector of the charging device according to the invention, the layer structure suitably has a metallic layer which is arranged facing away from the flat side. For example, the thickness of the dielectric area can be reduced by half by being connected to the metallic layer. In this way, as is known per se, the dielectric layer can be formed as a “mirror dielectric waveguide” by means of the metallic layer.

Suitably the layered structure has a layer opposite the flat side which is formed with a metamaterial. In particular, the metamaterial can be metallic, with this metamaterial forming a ground plane which is spatially structured in a manner known per se to avoid eddy currents being formed.

In the loading device according to the invention, the body of the object detector is expediently designed as a flat part with narrow sides, with the detection device(s) being or being arranged on or along at least one, preferably all, of the narrow sides. The body is particularly preferably a plate which has narrow sides in the form of edges. The detection device/s is/are then arranged on one, several or all edges. Suitably the detection device(s) are microwave receivers.

The detection device(s) is or are expedient for detecting a field strength and/or an energy and/or a power and/or an intensity and/or an amplitude and/or phase of received electromagnetic waves, in particular received microwaves, or one or more variables, which depend on the above variables, formed.

In the case of the object detector of the charging device according to the invention, the dielectric region is preferably formed with a dielectric constant of at least 1.5 and/or at most 10. In particular, the dielectric region is formed with a dielectric constant of at least 2 and/or at most 5, preferably at most 3.

The dielectric area is preferably formed with or from plastic. In a likewise preferred development of the invention, the dielectric area is formed with or from ceramic. The dielectric area is particularly preferably formed with or from a plastic/ceramic composite.

The charging device according to the invention is preferably a primary charging device.

Alternatively and also preferably, the charging device according to the invention is a secondary charging device.

In the case of the charging device according to the invention, at least the flat side is expediently oriented obliquely, preferably almost or completely perpendicularly, to the direction of a charging magnetic field of the charging coil at the location of the flat side.

In the charging device according to the invention, the charging coil preferably has a coupling side which is designed for inductive coupling to a further charging coil of a corresponding charging device, with at least the flat side being arranged on the side of the coupling side of the charging coil and oriented away from the coupling side.

The method according to the invention is a method for inductively charging an electric vehicle in particular by means of a primary charging device and a secondary charging device via an air gap located between the primary and secondary charging device, in which a charging device according to the invention as described above is used as the primary and/or secondary charging device, the object detector is used for detecting, in particular for location detection, an object at or within the air gap, with electromagnetic waves being fed into the dielectric area by means of the wave source, at least one variable dependent on the propagation of the electromagnetic waves in the dielectric area being recorded by means of the at least one detection device is and by means of the evaluation device depending on this size on a presence and / or the position, at least along the flat side, of the object and / or near d he flat side is closed.

In the method according to the invention, the object detector is preferably used for the detection, in particular for the location detection, of a metallic object. Alternatively or additionally and likewise preferably, the object detector is used for the detection, in particular for the location detection, of an object which has a higher dielectric constant than the dielectric region of the body.

In the method according to the invention, at least the dielectric region of the body is preferably fed by means of at least one coupler and/or by means of at least one waveguide feed and/or by means of coupling pins and/or by means of slot couplings.

In the method according to the invention, at least one propagation time of a signal of the electromagnetic waves to the object and/or from the object to the at least one detection device is suitably determined, the propagation time being used to determine the position of the object by means of the evaluation device. Such a signal is expediently implemented by means of a wave pulse, in particular a microwave pulse.

The dielectric area is expediently fed in continuous wave mode (CW=continuous wave) or FMCW mode or in pulses.

• 1 einen Objektdetektor einer erfindungsgemäßen Ladevorrichtung zur Durchführung eines erfindungsgemäßen Verfahrens zum induktiven Laden eines Elektrofahrzeugs schematisch in einer perspektivischen Darstellung,
• 2 ein Feldverteilungsbild zu einem bestimmten Zeitpunkt des sich innerhalb eines dielektrischen Körpers des Objektdetektors gemäß 1 ausbildenden Mikrowellenfeldes schematisch im Längsschnitt,
• 3 ein Feldverteilungsbild zu einem bestimmten Zeitpunkt des sich innerhalb eines dielektrischen Körpers des Objektdetektors gemäß 1 ausbildenden Mikrowellenfeldes schematisch im Querschnitt,
• 4 den Objektdetektor gemäß 1 schematisch in einer perspektivischen Darstellung bei auf dem dielektrischen Körper angeordnetem metallischem Objekt,
• 5 ein Feldverteilungsbild zu einem bestimmten Zeitpunkt des sich innerhalb des dielektrischen Körpers des Objektdetektors gemäß 1 in der Situation gem. 4 ausbildenden Mikrowellenfeldes schematisch im Längsschnitt,
• 6 ein Feldverteilungsbild zu einem bestimmten Zeitpunkt des sich innerhalb des dielektrischen Körpers des Objektdetektors gemäß 1 in der Situation gem. 4 ausbildenden Mikrowellenfeldes schematisch im Querschnitt,
• 7 ein Feldverteilungsbild zu einem bestimmten Zeitpunkt des sich innerhalb des dielektrischen Körpers des Objektdetektors gemäß 1 ausbildenden Mikrowellenfeldes schematisch im Längsschnitt bei auf dem dielektrischen Körper angeordnetem dielektrischem Objekt,
• 8 ein Feldverteilungsbild zu einem bestimmten Zeitpunkt des sich innerhalb des dielektrischen Körpers des Objektdetektors gemäß 1 in der Situation gem. 7 ausbildenden Mikrowellenfeldes schematisch im Querschnitt sowie
• 9 eine erfindungsgemäße Ladevorrichtung bei der Durchführung des erfindungsgemäßen Verfahrens zum induktiven Laden eines Elektrofahrzeugs schematisch im Querschnitt.

The invention is explained in more detail below using an exemplary embodiment illustrated in the drawing. Show it:

• 1 an object detector of a charging device according to the invention for carrying out a method according to the invention for inductive charging of an electric vehicle schematically in a perspective view,
• 2 according to a field distribution image at a certain point in time within a dielectric body of the object detector 1 forming microwave field schematically in longitudinal section,
• 3 according to a field distribution image at a certain point in time within a dielectric body of the object detector 1 forming microwave field schematic in cross section,
• 4 according to the object detector 1 schematically in a perspective view with the metallic object arranged on the dielectric body,
• 5 according to a field distribution image at a specific point in time located within the dielectric body of the object detector 1 in the situation acc. 4 forming microwave field schematically in longitudinal section,
• 6 according to a field distribution image at a specific point in time located within the dielectric body of the object detector 1 in the situation acc. 4 forming microwave field schematic in cross section,
• 7 according to a field distribution image at a specific point in time located within the dielectric body of the object detector 1 forming microwave field schematically in longitudinal section with the dielectric object arranged on the dielectric body,
• 8th according to a field distribution image at a specific point in time located within the dielectric body of the object detector 1 in the situation acc. 7 forming microwave field schematically in cross section and
• 9 a charging device according to the invention in the implementation of the method according to the invention for inductive charging of an electric vehicle schematically in cross section.

the inside 1 Illustrated object detector 5 of the charging device according to the invention (see 9 ) has a dielectric body in the form of a dielectric plate 10 with two flat sides 15, 20, which are delimited by four narrow sides 25, 30, 35, 40 of the plate 10. The plate 10 is designed as a flat cuboid. In 1 (Not shown explicitly), the plate 10 is surrounded by absorber material which absorbs microwaves. As in 2 shown, the microwave transmitter 50 emits microwaves 55, which propagate along the flat sides 15, 20. Because the plate 10 is surrounded by absorber material, no standing waves form in the plate 10 .

Will, as in 4 shown, a metallic object 60 is placed on the flat side 20 of the plate 10, the propagation behavior of the microwaves 55 changes within the plate 10 (see 5 ). To a certain extent, the metallic object 60 bundles microwaves 55 ( 5 and 6 ) and changes the further spatial propagation of the microwaves 55.

If the metallic object 60 is replaced by a dielectric object 65 ( 7 and 8th ), where the dielectric constant of the dielectric object 65 is higher than that of the dielectric material of the plate 10, the dielectric object 65 forms a kind of microwave sink, which efficiently decouples microwaves 55 propagating within the plate 10 from the plate 10.

Microwave receivers (only in 9 explicitly marked with the reference sign “RE”), which detect the previously explained modifications of the previously explained microwave field. The microwave receivers are signal-connected to an evaluation device which receives detection signals from the microwave receivers.

The dielectric plate 10 allows only an incomplete influence of the microwaves within the plate 10 along the flat sides 15, 20. An evanescent field forms on the flat sides 15, 20, which is caused by dielectric or metallic objects 65, 60 on the plate 10 as before explained is modified. From the resulting changed propagation of the microwave field within the plate 10 and the thereby changed detection signals of the microwave receivers, both the presence and the position of the metallic object 60 or the dielectric object 65 can be deduced by means of the evaluation device.

In the exemplary embodiment shown, the dielectric plate 10 consists of plastic, for example with a dielectric constant of 2.3. In further exemplary embodiments that are not shown specifically, the plate 10 can consist of a different dielectric, such as ceramic or a ceramic-plastic composite. The location detection as described above is supplemented by propagation time measurements, as are known per se from radar technology. Signals of the electromagnetic waves 55 scattered within the plate 10 are used for this purpose. The location of the metallic object 60 or the dielectric object 65 can also be determined by means of these propagation times used.

In other exemplary embodiments that are not specifically shown, reference can be made to the 1 down-facing flat side 15 of the dielectric plate 10 a metallic layer may be applied. In this exemplary embodiment, the thickness of the dielectric plate 10 is reduced, which forms a “mirror dielectric waveguide” together with the metallic layer.

In these last-mentioned exemplary embodiments, the metallic layer is in the form of a metallic metamaterial. The metallic layer forms a ground surface which is spatially structured in a manner known per se to prevent eddy currents from forming.

In the 9 illustrated charging device according to the invention is a primary charging device, ie it comprises a primary charging coil PLS, which provides energy for a secondary charging device with a secondary charging coil SLS. The charging device according to the invention shown forms a charging station for electric vehicles EFZ.

The primary charging coil PLS of the charging device is designed as a flat coil and lies flat on a base B of the charging device. The side of the primary charging coil PLS pointing away from the floor B forms a coupling side of the primary charging coil PLS, from which energy can be transmitted by means of a charging magnetic field to a secondary charging coil of an electric vehicle EFZ and which points in the direction of an air gap that forms when charging with an electric vehicle.

The plate 10 of the object detector 5 of the charging device adjoins the coupling side of the primary charging coil. The flat side 20 of the plate 10 facing away from the primary charging coil PLS delimits an air gap LS on the bottom side during inductive charging. On the other hand, the air gap LS is delimited by a secondary charging coil SLS on an electric vehicle EFZ driven to the charging station. Objects O located on the plate 10 of the object detector 5, such as foreign bodies, animals or the like, can be detected with the object detector 5 as described above. The air gap LS can thus be reliably and robustly monitored using the charging device according to the invention.

Claims (14)

Charging device for inductive charging, in particular of an electric vehicle (EV), comprising a charging coil (LS) for inductive charging and an object detector (5), the object detector (5) having a body with at least one dielectric region (10) with a flat side ( 20), at least one wave source (50) feeding the dielectric region (10) with electromagnetic waves (55), as well as a detection device for detecting at least one variable dependent on the propagation of the electromagnetic waves in the dielectric region (10) and an evaluation device, wherein the evaluation device is designed to infer the presence and/or the position, at least along the flat side, of an object on and/or near the flat side (20) as a function of this at least one variable, the dielectric region (10) being at least partially surrounded by an absorber material. charger after claim 1 in which the body and/or at least the dielectric area (10) of the body has or is a flat part, in particular a plate. Charging device according to one of the preceding claims, in which the body has a layer structure, in particular with a dielectric layer with the flat side (20). charger after claim 3 , in which the layer structure of the flat side (20) facing away from a metallic layer. Loading device according to one of claims 3 or 4 , in which the layer structure of the flat side (20) facing away from a layer formed with a metamaterial. Loading device according to one of the preceding claims, in which the body is designed as a flat part with narrow sides (25, 30, 35, 40). and the detection device(s) is or are arranged on or along at least one, preferably all of the narrow sides (25, 30, 35, 40). Charging device according to one of the preceding claims, in which the detection device is designed to detect the transit time of a signal of the electromagnetic waves (55) and the evaluation device is designed to determine the position, at least along the flat side, of an object (60; 65) from the detected transit time is. A charging device according to any one of the preceding claims which is a primary or a secondary charging device. Charging device according to one of the preceding claims, in which at least the flat side (20) is oriented obliquely, preferably almost or completely perpendicularly, to the direction of a charging magnetic field of the charging coil (PLS) at the location of the flat side. Charging device according to one of the preceding claims, in which the charging coil (PLS) has a coupling side which is designed for inductive coupling to a further charging coil of a corresponding charging device, at least the flat side (20) being arranged on the coupling side of the charging coil (PLS) and the Coupling side is oriented away. Method for inductive charging, in particular of an electric vehicle, by means of a primary charging device and a secondary charging device via an air gap located between the primary and secondary charging device, in which a charging device according to one of the preceding claims is used as the primary and/or secondary charging device, the object detector (5) is used to detect, in particular to detect the location of, an object (60; 65) on or within the air gap, with the wave source (50) feeding electromagnetic waves (55) into the dielectric region (10), the at least one detection device at least a variable dependent on the propagation of the electromagnetic waves (55) in the dielectric region (10) is detected and the presence and/or the position, at least along the flat side, of the object (60; 65 ) on and/o which is closed near the flat side (20). Method according to the preceding claim, in which the object detector (5) is used to detect, in particular to detect the location of, a metallic object (60). Method according to any of the preceding Claims 11 or 12 in which the object detector is used to detect, in particular to detect the location of, an object (65) which, compared to the dielectric constant of the dielectric region of the body, has a higher or the same dielectric constant. Method according to any of the preceding Claims 11 until 13 , in which at least one transit time of a signal of the electromagnetic waves (55) to the object (60; 65) and/or from the object (60; 65) to the at least one detection device is determined, the transit time for determining the position of the Object (60; 65) is used.

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