Inductive charging station and method for controlling an inductive charging station

Abstract

Inductive charging station (1) comprising a control unit (2) and a primary coil (3), wherein the control unit (2) is configured to control a current flow through the primary coil (3), wherein the inductive charging station (1) has a mains connection (9), wherein the inductive charging station (1) has at least one safety circuit (4) independent of the control unit (2), which is configured to control at least one switching element (6-8) that interrupts the current flow through the primary coil (3), wherein the inductive charging station (1) has at least one detection device (5) that is connected to the safety circuit (4) via data transmission, wherein the safety circuit (4) is configured to control the at least one switching element (6-8) depending on the signals of the at least one detection device (5), wherein the control unit (2) is configured such that the at least one switching element (6-8) is opened.when a magnetic field of the primary coil (3) is detected and a missing and / or impossible charging process is inferred from the signals of the detection device (5), wherein the safety circuit (4) is designed such that it is activated by a magnetic field of the primary coil (3).

Description

The invention relates to an inductive charging station and a method for controlling an inductive charging station.Inductive charging stations are usually used for inductively charging electric or hybrid vehicles. These have a primary coil which is arranged, for example, below a charging plate. The current flow through the primary coil is electrically controlled by a control unit with a corresponding power, wherein the control unit has a grid connection, wherein the grid makes the electrical energy available for the charging process. The energized primary coil then generates a magnetic field that generates a voltage in a secondary coil in a vehicle to be charged. The magnetic field strengths occurring in this case can be very large. Therefore, this magnetic field can have an influence on objects such as humans (e.g. with heart pacemakers) or animals. Further interfering objects can be metallic objects, for example.To solve this problem, GB 2510125 A provides a charge monitoring device disposed in the vehicle. If the vehicle-side charge monitoring device then detects people in or next to the vehicle or animals, this is communicated to the inductive charging station and the control unit accordingly reduces the charging power.US 2016 / 0109564 A1 discloses an inductive charging station which has a vehicle-controlled radar device by means of which interfering objects such as humans, animals or metallic objects are detected, wherein the control unit adjusts the charging power as a function of the radar signals. The advantage of this charging station is that interfering objects are detected independently of the vehicle equipment.DE 10 2014 005 531 A1 discloses a charging arrangement for inductively charging the energy store of a vehicle, wherein a primary winding can be fed by an inverter, the control signals of which are generated by signal electronics and which can be supplied from a supply voltage provided by a switched-mode power supply, wherein the supply voltage is a unipolar voltage, in particular a direct voltage. In this case, the supply voltage can be switched off by a detection module or at least the supply voltage can be switched off. The detection module is connected to a means for detecting the current impressed into the primary winding and / or to a means for detecting the magnetic field generated by the primary winding.DE 10 2014 207 427 A1 discloses a device for detecting at least one interference body in a system for inductive energy transmission, wherein the system for inductive energy transmission comprises at least one primary coil unit for generating at least part of an electromagnetic power transmission field, wherein the device comprises at least one interference body detector means. The at least one interference body detector means comprises at least one excitation coil means for generating an excitation field and at least one detector coil means which is assigned to the at least one excitation coil means. Furthermore, the device comprises at least one evaluation means for detecting a coupling state between the at least excitation coil means and the at least one detector coil means and / or for detecting a change in the coupling state, wherein the interference body is detectable as a function of the coupling state and / or the change in the coupling state. Furthermore, the device comprises at least one compensation means for taking into account an electromagnetic influence of the primary coil unit and / or the secondary coil unit on the coupling state between the at least one excitation coil means and the at least one detector coil means.DE 10 2015 207 992 A1, EP 2 803 522 A1 and US 2013 / 0009475 A1 disclose further inductive charging stations with object detection.The invention is based on the technical problem of creating an inductive charging station and of making available a method for controlling an inductive charging station, by means of which method the safety can be further increased.The solution of the technical problem results from an inductive charging station having the features of claim 1 and a method having the features of claim 6.The inductive charging station comprises a control unit and a primary coil, wherein the control unit is configured to control a current flow through the primary coil, wherein the inductive charging station has a mains connection. Furthermore, the inductive charging station has at least one safety circuit which is independent of the control unit and is designed in such a way as to actuate at least one switching element which interrupts the current flow through the primary coil. This ensures that even in the event of a fault or a manipulation of the control unit, the magnetic field of the primary coil can be switched off or is not built up at all. The at least one switching element is preferably designed as a relay. However, other switching elements such as power semiconductors are also possible in principle.The inductive charging station has at least one detection device which is connected to the safety circuit by data technology. The data connection can be wired or via an air interface. The safety circuit is designed in such a way that the at least one switching element is controlled as a function of the signals of the at least one detection device. It should be noted here that a plurality of detection devices can also be assigned to the at least one safety circuit.The control unit is designed such that the at least one switching element is opened when a magnetic field of the primary coil is detected and a missing or possible charging process is inferred from the signals of the detection device. The magnetic field can be detected, for example, by an induction coil. If, for example, the detection device then detects no vehicle and / or an interfering object such as a cable or a human, the current flow through the primary coil is interrupted by the switching element. In the combination, at least the safety circuit must enable the charging process and can then cancel it again at any time if the preconditions change (for example a vehicle moves away and the primary coil is energized further).Furthermore, the safety circuit is designed such that it is activated by a magnetic field of the primary coil. As a result, the safety circuit is only switched on when a primary field is also present, which correspondingly leads to a low quiescent current requirement of the safety circuit.In one embodiment, the at least one switching element is arranged between the mains connection and the control unit and / or between the control unit and the primary coil and / or between the control unit and a supply voltage connection of the control unit. The advantage of the switching element at the mains connection is that the mains voltage is switched off, so that internal short circuits also do not present any problem. The advantage of the switching element on the primary coil, on the other hand, is that the switching process is faster during the switching on, since the control unit does not have to be started up.In addition, the safety circuit is designed such that the at least one switching element is not closed until a desired and possible charging process is concluded from the signals of the detection device. For example, the detection device is a camera that detects a vehicle to be loaded. Alternatively, these charge request signals can detect. For example, the vehicle electronically or optically transmits a signal that expresses the charging request. Alternatively or additionally, the vehicle can be designed with an RFID tag or a vehicle to be charged is detected by means of light barriers or induction coils. In this embodiment, the safety circuit is thus connected upstream, i.e. only when it enables the charging process can the control unit supply current to the primary coil.In a further embodiment, the detection device is designed to detect a charge request signal which is independent of a charge request signal for the control unit, which increases safety by increased redundancy. For example, the vehicle can generate a first and a second charge request signal, one signal being for the control unit and the other for the safety circuit. The two signals can also be very different, e.g. optical and electrical. Alternatively, the safety circuit receives the load request signal from an online service to which the driver has logged in.In a further embodiment, the detection device is designed to detect interfering objects such as people, animals or metallic objects.The method for controlling an inductive charging station, wherein the charging station has a control unit and a primary coil and the control unit controls a current flow through the primary coil, is characterized in that the inductive charging station is monitored by means of a safety circuit independent of the control unit, wherein the safety circuit actuates a switching element that interrupts the current flow through the primary coil, wherein in the event of a fault the switching element is opened or remains open, wherein at least one detection device is connected to the safety circuit by data technology, wherein the safety circuit actuates the at least one switching element as a function of the signals of the at least one detection device, wherein the at least one switching element is opened when a magnetic field of the primary coil is detected and a missing and / or impossible charging process is concluded from the signals of the detection device, wherein the safety circuit is activated by a magnetic field of the primary coil. Fault case means in particular that no vehicle with a charging request is present and / or that a fault object is present.With regard to further embodiments of the method, reference is made to the preceding explanations relating to the inductive charging station.The invention is explained in more detail below with reference to preferred exemplary embodiments. The single FIGURE shows a schematic block diagram of an inductive charging station.The inductive charging station 1 has a control unit 2, a primary coil 3, a safety circuit 4 having a detection device 5, and a first switching element 6, a second switching element 7 and a third switching element 8. In this case, the first switching element 6 is arranged between a mains connection 9 and the control unit 2. The second switching element 7 is arranged between the control unit 2 and the primary coil 3, and the third switching element 8 is arranged between a supply voltage terminal for the control unit 2 and the control unit 2. The switching elements 6- 8 are preferably designed as relays. It should be noted here that in principle one switching element 6- 8 is sufficient. FIG. 1 shows that the control unit 2 draws its supply voltage from the mains voltage. This is not obligatory. Thus, alternatively or additionally, a battery can provide the supply voltage. The primary coil 3 is arranged below a base plate 10. The voltage supply of the safety circuit 4, not shown, can be a local, autonomous voltage supply (e.g. a battery) or can also be effected via the mains voltage.The control unit 2 contains power electronics and can supply current to the primary coil 3 when the switching elements 6- 8 are closed. In this case, the control unit 2 can set parameters for the current and also completely switch it off.In a first embodiment, the switching elements 6- 8 are open, wherein it is assumed below that only the switching element 6 is present. If a vehicle now approaches, which wants to be charged inductively, this is detected by the detection device 5 and transmitted to the safety circuit 4. In addition, the detection device 5 can search the base plate 10 for interfering objects (e.g. people, animals or metallic objects) in the region of the primary coil 3. For this purpose, the detection device 5 can have a camera and / or radar and / or ultrasonic sensors. The approach of a vehicle with a charging request can be carried out by the detection device 5 in very different ways, which can also be combined with one another as desired. For example, the vehicle may have an RFID tag or emit a specific electrical or optical signal. Alternatively or additionally, the detection device 5 receives a signal of an online service, with which it is communicated that a vehicle with a charging request is located in its area.If both conditions are fulfilled (vehicle with a charging request and no interfering object), the safety circuit 4 generates a control signal in order to close the switching element 6. The vehicle can then send a further signal, with which the charging request and desired charging parameters are transmitted to the control unit 2; depending on the charging parameters, the control unit 2 then adjusts the current through the primary coil 3. In this case, it can also be provided that the vehicle only emits a signal which is repeated. In this case, the safety circuit 4 then closes the switching element 6 when the signal is initially received by the detection device 5. Subsequently, after the control unit 2 starts up, the vehicle sends the signal again. In embodiments where the control unit 2 has a supply voltage independent of the mains voltage, the transmission of a single signal is sufficient in this case, since the control unit 2 can receive and store this even when the switching element 6 is open.In an alternative embodiment, the switching element 6 is closed as standard. The control unit 2 then energizes the primary coil 3 in the presence of a vehicle with a charging request and disconnects the current in the primary coil 3 if no vehicle is present. The disconnection is effected by means of switching elements in the control unit 2. the safety circuit 4 is also deactivated as standard. If, on the other hand, the detection device 5 detects a magnetic field that is generated by the primary coil 3, the detection device 5 activates the safety circuit 4. This can be done, for example, by means of a further sensor system of the detection device 5 (e.g. camera). If a vehicle is present, the shifting element 6 remains closed. In this case, it can additionally be detected whether no interfering objects are also present. If no vehicle is detected, errors in the control unit 2 or a manipulation are inferred and the safety circuit 4 opens the switching element 6, so that the primary coil 3 can no longer be energized due to the missing mains voltage.The safety circuit 4 completely independent of the control unit 2 can thus improve the safety at an inductive charging station 1, since errors or manipulations of the control unit 2 are detected and the current through the primary coil 3 can be interrupted independently of the control unit 2.List of reference characters1 Inductive charging station 2 Control unit 3 Primary coil 4 Safety circuit 5 Detection device 6 Switching element 7 Switching element 8 Switching element 9 Mains connection 10 Base plate

Claims

Inductive charging station (1) comprising a control unit (2) and a primary coil (3), wherein the control unit (2) is designed to control a current flow through the primary coil (3), wherein the inductive charging station (1) has a mains connection (9), wherein the inductive charging station (1) has at least one safety circuit (4) which is independent of the control unit (2) and is designed to actuate at least one switching element (6-8) which interrupts the current flow through the primary coil (3), wherein the inductive charging station (1) has at least one detection device (5) which is connected to the safety circuit (4) by data technology, wherein the safety circuit (4) is designed to actuate the at least one switching element (6-8) on the basis of the signals from the at least one detection device (5), wherein the control unit (2) is designed such that the at least one switching element (6-8) is opened, if a magnetic field of the primary coil (3) is detected and a missing and / or impossible charging process is deduced from the signals of the detection device (5), wherein the safety circuit (4) is designed such that it is activated by a magnetic field of the primary coil (3).Inductive charging station according to Claim 1, characterized in that the at least one switching element (6) is arranged between the mains connection (9) and the control unit (2) and / or the control unit (2) and the primary coil (3) and / or the control unit (2) and a supply voltage connection of the control unit (2).Inductive charging station according to Claim 1 or 2, characterized in that the safety circuit (4) is designed in such a way that the at least one switching element (6-8) is not closed until a desired and possible charging process is concluded from the signals of the detection device (5).Inductive charging station according to one of the preceding claims, characterized in that the detection device (5) is designed to detect a charging request signal which is independent of a charging request signal for the control unit (2).Inductive charging station according to one of the preceding claims, characterized in that the detection device (5) is designed to detect interfering objects.Method for controlling an inductive charging station (1), wherein the inductive charging station (1) has a control unit (2) and a primary coil (3), wherein the control unit (2) controls a current flow through the primary coil (3), wherein the inductive charging station (1) is monitored by means of a safety circuit (4) independent of the control unit (2), wherein the safety circuit (4) actuates a switching element (6-8) which interrupts the current flow through the primary coil (3), wherein in the event of a fault the switching element (6-8) is opened or remains open, wherein at least one detection device (5) is connected to the safety circuit (4) by data technology, wherein the safety circuit (4) actuates the at least one switching element (6-8) as a function of the signals of the at least one detection device (5), wherein the at least one switching element (6-8) is opened, if a magnetic field of the primary coil (3) is detected and a missing and / or impossible charging process is deduced from the signals of the detection device (5), wherein the safety circuit (4) is activated by a magnetic field of the primary coil (3).

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