DE102018217732A1 - Inductive energy transfer device, charging system - Google Patents

Abstract

The invention relates to an inductive energy transmission device (6), in particular for a charging station (3) for motor vehicles (2), with an energizable primary coil (5) which is designed to be energized in a secondary coil (8), in particular of the motor vehicle ( 2) to induce an electric current, and with a sensor device (13) for monitoring an intermediate space (11) between the primary coil (5) and the secondary coil (8) for foreign objects (12). It is provided that the sensor device (13) is designed to detect infrared radiation.

Description

The invention relates to an inductive energy transmission device, in particular from a charging station for motor vehicles, with an energizable primary coil, which is designed to induce an electrical voltage when energized in a secondary coil, in particular of the motor vehicle, and with a sensor device for monitoring an intermediate space between Primary coil and secondary coil on foreign objects.

State of the art

Inductive energy transmission devices of the type mentioned at the outset are known from the prior art. For the electrical charging of energy stores of electrically operated motor vehicles, it is known to make electrical contact with them by means of a charging cable or to carry out contactless or contactless energy transmission. In the case of contactless energy transmission, the induction principle is used, in which a primary coil is energized, which induces a current or a voltage in a secondary coil which is arranged at a distance from the primary coil. If the secondary coil is connected to the charging system of the motor vehicle, the induced current is used to charge the energy storage device of the motor vehicle. Typically, the primary coil is either embedded in a street floor or shaped as a charging plate placed on the floor and connected to a local power network by means of suitable electronics. The secondary coil is usually mounted in the underbody of a motor vehicle and in turn is connected to the vehicle battery or the energy storage device of the motor vehicle by means of suitable electronics. For energy transmission, the primary coil generates a high-frequency alternating magnetic field, which penetrates the secondary coil and induces a corresponding current there. The magnetic alternating fields that arise in the air gap during the transmission can induce electrical eddy currents in metallic objects that are located in the space between the primary coil and the secondary coil. Through ohmic losses, these heat up with foreign objects made of metal. The heating poses a danger not only for personal safety, but also for the operational safety of the motor vehicle or the charging system. In addition, there may also be biological foreign objects in the intermediate space, such as animals, human body parts or the like, which are then exposed to the magnetic fields .

For the detection of foreign objects, it is therefore known to provide a sensor device which is designed to detect foreign objects in the intermediate space. As a sensor device, it is known, for example, to provide motion detectors or object detection devices, such as laser scanners, video cameras or the like.

Disclosure of the invention

The energy transmission device according to the invention with the features of claim 1 has the advantage that with a simple and inexpensive sensor device, both metallic foreign objects and biological foreign objects can be reliably detected in the space between the primary coil and the sensor coil. It is particularly advantageous that a single type of sensor can be used, so that the number of parts is reduced and the evaluation is also simplified. For this purpose, it is provided according to the invention that the sensor device is designed to detect infrared radiation. The sensor device thus reacts to heat that can be radiated both from biological foreign bodies and from metallic foreign bodies. It is thus possible to use the sensor device to detect both living beings or biological foreign bodies and also electrically conductive or metallic foreign objects. By detecting infrared radiation, the foreign objects can also be detected at a certain distance, ie also in the vicinity of the primary coil, so that foreign objects located next to the primary coil can also be detected. This is advantageous because the stray magnetic field often protrudes beyond the area of the primary coil during a charging process. In addition, the monitoring of the infrared radiation allows a timely reaction, which means that countermeasures such as the termination of a charging process can be carried out quickly when a foreign body is detected, for example. Because the sensor device is assigned to the primary coil, it is also able to detect the secondary coil, insofar as it is arranged opposite the primary coil, and thereby also detect, for example, overheating of the secondary coil. In this way, for example, temperature sensors that would otherwise be assigned to the secondary coil for monitoring them can be dispensed with. Because the temperature of the detected foreign object is determined with the aid of the infrared radiation, the charging process can also be carried out in a space in spite of the presence of a foreign object, in which case the power of the energy transfer is preferably reduced in order to avoid reaching a critical temperature of the foreign object. However, if the critical temperature is exceeded, the charging process is preferably stopped completely.

The sensor device preferably has at least one for detecting the infrared radiation Thermopile, a bolometer or a pyroelectric sensor. These sensors are known components which can therefore be used cost-effectively to implement the sensor device. In addition, these sensor types also allow absolute temperature measurement, so that a distinction can also be made between different foreign objects. If, for example, an object temperature of approximately 36 ° C. is detected, it is recognized that there is a biological object, in particular a living being, in the intermediate space. If the temperature of the foreign object in the magnetic field increases, it is recognized that it is a metal object heated by the magnetic field.

According to a preferred development of the invention, the sensor device alternatively or additionally has at least one temperature sensor which has an infrared radiation-absorbing temperature sensor.

The combination of a highly infrared-absorbing material of the temperature sensor with a temperature sensor assigned to it, such as NTC, PTC, semiconductor diode or the like, offers the advantage that heat radiation and contact heat, which arises, for example, from a heated metallic foreign object lying on top, are detected at the same time can be.

According to a preferred development of the invention, the sensor device has a large number of identical or different sensors, which are arranged to form a sensor field in only one common plane. Such a sensor array realizes a precise local resolution of the foreign object detection, so that not only the presence of a foreign object, but also the location and optionally the dimensions of the foreign object are determined. Countermeasures can thereby be carried out particularly advantageously.

The sensors are preferably arranged uniformly distributed in the sensor field, in particular in the form of a matrix, so that advantageous coverage of the sensor area, in particular of the intermediate space or the primary coil, is ensured.

The sensors are particularly preferably arranged parallel to the primary coil on the side associated with the secondary coil. This ensures that the sensors monitor the space on the side of the primary coil facing the secondary coil and that foreign object detection is reliably ensured.

The sensor field preferably extends at least over the primary coil, so that the entire area of the primary coil is covered by the sensor field and reliable foreign object detection is ensured in this area.

Furthermore, it is preferably provided that the sensors are arranged so as to be protected by a cover, in particular by a housing, the cover being at least partially transparent to infrared radiation. The cover and the housing protect the sensors from external influences such as dirt and moisture. This ensures a long service life for the sensor device. The cover is expediently permeable to infrared radiation, at least in sections, so that the sensors can perform the function described above. To achieve the permeability of the cover, for example, transparent sections of the cover can be used.

In particular, the cover for each of the sensors has a window that is transparent to infrared radiation. This is made of HDPE (high density polyethylene), for example, to ensure both the protective function and the transmission of infrared radiation. The respective window is expediently arranged in an opening of the cover provided for this purpose. The sensors are preferably arranged on a circuit board, which is arranged opposite the cover, so that each sensor is opposite an opening of the cover or one of the windows.

The respective window is particularly preferably designed as a focusing lens, in particular as a Fresnel lens. The lens focuses the infrared radiation on the respective sensor, thus increasing the resolution of the sensor device and the area to be monitored. The preferred design of the lens as a Fresnel lens saves material and height, so that a cost-effective and space-saving design is guaranteed.

According to an alternative embodiment of the invention, the cover as a whole is transparent to infrared radiation, so that there is no need to provide individual openings and windows. This further reduces manufacturing costs. A lens, in particular a Fresnel lens, is preferably integrated in the cover of each of the sensors. This is achieved, for example, by bulging the cover at a point opposite the respective sensor. The particularly convex bulge of the individual Lenses can be directed inwards or outwards.

According to a preferred development of the invention, a magnetic field shield is assigned to each of the sensors. Because the sensor device is arranged on the side of the primary coil facing the secondary coil, the alternating magnetic field also penetrates the sensor device. The magnetic field shield ensures that the sensors are not influenced by the magnetic field. In particular, as a magnetic field shield, a ferite shape is assigned to the respective sensor, which guides the magnetic field past the sensor.

The selective charging system with the features of claim 13 is characterized by the inventive design of the energy transmission device. This results in the advantages already mentioned.

• 1 ein induktives Ladesystem für ein Kraftfahrzeug in einer vereinfachten Seitendarstellung,
• 2 eine vorteilhafte Sensoreinrichtung des Ladesystems in einer Draufsicht,
• 3 eine vereinfachte Detailansicht der Sensoreinrichtung gemäß einem ersten Ausführungsbeispiel,
• 4 eine vereinfachte Detailansicht der Sensoreinrichtung gemäß einem zweiten Ausführungsbeispiel,
• 5 eine vereinfachte Detailansicht der Sensoreinrichtung gemäß einem dritten Ausführungsbeispiel,
• 6 eine weitere Detailansicht der Sensoreinrichtung gemäß einer vorteilhaften Weiterbildung und
• 7 eine weitere Detailansicht der Sensoreinrichtung gemäß einem weiteren Ausführungsbeispiel.

Further advantages and preferred features and combinations of features result in particular from what has been described above and from the claims. The invention will be explained in more detail below with reference to the drawing. Show this

• 1 an inductive charging system for a motor vehicle in a simplified side view,
• 2nd an advantageous sensor device of the charging system in a plan view,
• 3rd 3 shows a simplified detailed view of the sensor device according to a first exemplary embodiment,
• 4th 2 shows a simplified detailed view of the sensor device according to a second exemplary embodiment,
• 5 3 shows a simplified detailed view of the sensor device according to a third exemplary embodiment,
• 6 another detailed view of the sensor device according to an advantageous development and
• 7 a further detailed view of the sensor device according to another embodiment.

1 shows a simplified side view of a charging system 1 for an electric motor vehicle 2nd . The charging system 1 has a stationary charging station 3rd on, which is electrically connected to a power grid of a local electricity supplier. The charging station 3rd has power electronics with a control unit 4th as well as a primary coil 5 as an inductive energy transmission device 6 on. The control unit 4th is designed to energize or control the primary coil in such a way that it generates an electrical magnetic field which can be used to transmit electrical energy.

The charging system 1 also has a charging device 7 on the motor vehicle 2nd is associated. The charger 7 has a secondary coil 8th on that electrically with a control unit 9 of the motor vehicle 2nd as well as with an energy storage 10th connected is.

The secondary coil is located 8th above the primary coil 5 , as in 1 shown, and becomes the primary coil 5 controlled to generate the high-frequency alternating magnetic field, the magnetic field also penetrates the secondary coil 8th , being in the secondary coil 8th an electrical current or an electrical voltage is induced by the control device 9 the energy storage 10th is fed to its charging. The primary coil 8th is the vehicle floor of the motor vehicle 2nd assigned so that it is as close as possible to the primary coil 5 lies, or thus the smallest possible air gap between the primary coil 5 and secondary coil 8th is present. In the space 11 whose height is determined by the distance from the primary coil 5 to secondary coil 8th foreign objects can be defined 12th reach. These foreign objects can be, for example, biological foreign objects such as living things that run during the loading process or before a loading process onto the area of the road in which the primary coil is located 5 is arranged as in 1 shown as an example. Alternatively, it can also be metallic or electrically conductive foreign objects 12th act that in the space 11 lie.

If the charging process is carried out, the electromagnetic field causes the metallic foreign object 12th charged and warmed or a biological foreign object 12th is loaded by this high-frequency alternating magnetic field.

To the charging process, therefore, if necessary, i.e. if there is a foreign object 12th in the space 11 located to be able to bill or influence promptly, the transmission device has 6 one of the primary coil 5 assigned sensor device 13 on.

2nd shows a simplified top view of the primary coil 5 the charging station 3rd the sensor device 13 . This has a housing 14 on in which a variety of sensors 15 are evenly distributed around a sensor field 16 to build. The sensors 15 are all in a common plane parallel to the primary coil 5 .

According to the present exemplary embodiment, the sensors are 15 thermosensors that react to infrared radiation and are designed in particular as thermopiles, bolometers or pyroelectric sensors. As a result, absolute temperature measurement at a distance is also possible. The absolute measurement can also differentiate between different objects. As 2nd shows are the sensors 15 over the primary coil 5 arranged distributed so that on the one hand, the surroundings of the primary coil by the sensor device 13 is detectable, and on the other hand an exact local resolution over the surface of the primary coil 5 is guaranteed. Through the evenly distributed sensors 15 is thus a position as well as a size determination of the foreign object 12th in the space 11 guaranteed. It is also possible to go through the sensor field 16 to determine if the object is moving. With the sensor field arrangement, a much larger area can be monitored with the same opening angle and the same distance than with just a single sensor.

Through the housing 14 the sensor arrangement is protected from dirt and moisture. In particular, the sensors 15 through a housing wall that has a cover 17th forms, protected from the road. So that infrared measurement is still possible, the cover must be transparent to infrared rays at least in sections.

According to the embodiment of 3rd it is intended that the cover 17th a variety of openings 18th has, each with an opening 18th one of the sensors 15 assigned. Each of the openings 18th is through a window that is transparent to infrared rays 19th closed, so that moisture and dirt are not in the area of the sensors 15 in the housing 14 can reach.

In particular, the windows of which in 3rd only one is shown, designed as a lens, which infrared radiation to the sensor behind it 15 focused to increase the resolution and the area to be monitored. The lens is optional 20th designed as a Fresnel lens to save material and height.

4th shows a further embodiment of the sensor device 13 in a simplified detailed sectional view. According to this embodiment, it is provided that the cover 17th is made entirely of material that is permeable to infrared radiation, for example HDPE. The lenses 20th for the sensors 15 are there as convex bulges 21 on the side of the cover facing the secondary coil 17th educated. Alternatively, the bulges 21 also on the of the sensors 15 facing side of the cover 17th be trained.

5 shows a further embodiment, which differs from the previous embodiment in that the bulges 21 now the sensors 15 are facing and that the lenses 20th are designed as Fresnel lenses to advantageously focus or bundle infrared radiation to the sensors. In the figures, the infrared rays are indicated by arrows.

6 shows a further embodiment of the sensor device 13 , which is based on the embodiment 3rd differs in that the sensors are designed as temperature sensors, but each have a temperature sensor 22 have, which is made of an infrared radiation highly absorbent material. As a result, the temperature sensor is heated by the infrared radiation and this heating by the respective temperature sensor 15 detected. In this case, the temperature sensors can be designed, for example, as semiconductor diodes, NTC or PTC elements. This variant has the advantage that heat radiation and contact heat at the same time, for example by means of on the cover 17th overlying the foreign body 12th can be detected equally.

Because the sensors 15 placed above the primary coil to have an unrestricted field of view towards the secondary coil, they will also be from the primary magnetic field of the primary coil 5 flow through when it is energized. To affect the sensors 15 To avoid this, it is advantageous to use magnetic shielding 23 assigned. As in the exemplary embodiment of FIG 7 shown by way of example, for example in the form of a U-shaped ferrite element. The sensor 15 , especially thermal sensor, is on a circuit board 24th the sensor device 13 arranged and by the ferrite element 23 supported in front of the main magnetic field, because the ferrite conducts the main magnetic field around the sensor, as by magnetic field lines in 7 shown. In particular, only the sensors 15 with a magnetic shield 23 provided, which are located in a critical area of the magnetic field or primary coil, in which particularly high field forces can occur. This is the case, for example, with the sensors located further on the outer edge 15 such shielding is not absolutely necessary and is therefore preferably avoided for cost reasons where the magnetic field strength is less pronounced.

Claims (13)

Inductive energy transmission device (6), in particular for a charging station (3) for motor vehicles (2), with an energizable primary coil (5), which is designed to induce an electric current when energized in a secondary coil (8), in particular of the motor vehicle (2), and with a sensor device (13) for monitoring an intermediate space (11) between the primary coil (5) and the secondary coil ( 8) on foreign objects (12), characterized in that the sensor device (13) is designed to detect infrared radiation. Energy transmission device after Claim 1 , characterized in that the sensor device (13) has at least one thermopile, a bolometer or a pyroelectric sensor (15). Energy transmission device according to one of the preceding claims, characterized in that the sensor device (13) has at least one temperature sensor which has an infrared radiation-absorbing temperature sensor (22). Energy transmission device according to one of the preceding claims, characterized in that the sensor device (13) has a plurality of identical or different sensors (15) which are arranged in only one common plane to form a sensor field (16). Energy transmission device according to one of the preceding claims, characterized in that the sensors (15) are arranged uniformly distributed in the sensor field (16). Energy transmission device according to one of the preceding claims, characterized in that the sensors (15) are arranged parallel to the primary coil (5) on the side associated with the secondary coil (8). Energy transmission device according to one of the preceding claims, characterized in that the sensor field (16) extends at least over the primary coil (5). Energy transmission device according to one of the preceding claims, characterized in that the sensors (15) are arranged so as to be protected by a cover (17), in particular housing (14), the cover (17) being at least partially transparent to infrared radiation. Energy transmission device according to one of the preceding claims, characterized in that the cover (17) for each sensor (15) has a window (19) which is transparent to infrared radiation. Energy transmission device according to one of the preceding claims, characterized in that the window is designed as a focusing lens (20), in particular as a Fresnel lens. Energy transmission device according to one of the preceding claims, characterized in that the cover (17) is transparent to infrared radiation overall and in particular has an integrated lens (20) for each sensor (15). Energy transmission device according to one of the preceding claims, characterized in that at least some of the sensors are associated with a magnetic field shield (23). Inductive charging system (1) for a motor vehicle (2), with an energy transmission device (6), in particular associated with a charging station (3), for transmitting electrical energy and with a secondary coil (8), particularly associated with the motor vehicle, for receiving the electrical energy, characterized by the design the energy transmission device (6) according to one of the Claims 1 to 12th .

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