Electrical charging infrastructure

Abstract

The invention relates to an electrical charging infrastructure (12) for producing a conductive connection to a vehicle contact unit (16). The charging infrastructure (12) has a ground contact unit (18) which has a plate-type main body (26) and multiple contacts (30) that are arranged on a charging surface (28) of the main body (26). The multiple contacts (30) comprise power contacts (32) which are associated with at least one potential layer. The power contacts (32) are each connected in series to a contact switch (38). The contact switches (38) are designed as mirror contacts, such that every contact switch (38) comprises a main contact (40) and a monitoring contact (42) which are mechanically coupled but galvanically isolated from one another. The charging infrastructure (12) has a monitoring circuit (20) which is designed to monitor at least the respective switch position of the monitoring contacts (42) of the contact switches (38) which are associated with power contacts (32) that are not contacted when there is a conductive connection. The monitoring circuit (20) is designed to control a switch-off device (22).

Description

[0001] Electric charging infrastructure

[0002] The invention relates to an electrical charging infrastructure for establishing a conductive connection to a vehicle contact unit.

[0003] For at least partially electrically powered vehicles, such as plug-in hybrid vehicles and fully electric vehicles, the batteries must be charged regularly, preferably after every trip. To do this, the vehicle is connected to a suitable power source, typically using a plug, such as a so-called Type 2 plug, which must be manually inserted by a person into a corresponding socket on the vehicle.

[0004] Ground contact units for vehicle battery charging systems, which are provided on the ground, are also known from the prior art, for example, WO 2019 / 052962 A1. The ground contact units can automatically establish a conductive connection with a corresponding vehicle contact unit provided on the vehicle to be charged in order to charge the vehicle. The vehicle contact unit can be provided on the underbody of the vehicle, where it moves downwards to establish electrical contact with the ground contact unit.

[0005] For example, the ground contact unit is designed as a so-called matrix charging pad, as shown in WO 2019 / 052962 A1. For this purpose, the ground contact unit comprises a plurality of contact areas arranged in a matrix, wherein the contact areas can be contacted by means of the vehicle contact unit in order to establish an electrical connection between the ground contact unit and the vehicle contact unit. Depending on the contact point of the connector of the vehicle contact unit, the correspondingly occupied contact areas of the ground contact unit are switched on in order to establish the electrical connection via these contact areas. Typically, the occupied contact areas are switched on using separate relays assigned to each power contact of the ground contact unit.This results in a so-called matrix relay, which, among other things, ensures the safety-relevant requirements regarding the insulation distance of the individual switches. In addition, two relays are typically connected in series per power contact to ensure appropriate redundancy and reliability. Furthermore, the multiple relays ensure that the ground contact unit is ready to perform a charging process by first opening all relays so that all power contacts are potential-free.

[0006] However, the high number of relays and their wiring lead to correspondingly high costs.

[0007] The object of the invention is to make the charging infrastructure more efficient in terms of its structure.

[0008] The object is achieved according to the invention by an electrical charging infrastructure for establishing a conductive connection to a vehicle contact unit. The charging infrastructure has a ground contact unit comprising a plate-shaped base body and a plurality of contacts arranged on a charging surface of the base body against which the vehicle contact unit can come into contact. The plurality of contacts comprise at least power contacts assigned to at least one potential layer. The power contacts are each connected in series to a contact switch. The contact switches are each designed as mirror contacts, such that each contact switch comprises a main contact and a monitoring contact that are mechanically coupled but galvanically isolated from one another.The charging infrastructure has a monitoring circuit configured to monitor at least the respective switching position of the monitoring contacts of the contact switches assigned to power contacts that are not contacted when a conductive connection is present. The monitoring circuit is configured to control a shutdown device.

[0009] The basic idea of ​​the invention is to simplify the design of the ground contact unit in that the power contacts are assigned to only one contact switch instead of two relays connected in series. This allows the number of relays used to be significantly reduced, thus increasing efficiency and simultaneously reducing costs. The contact switches are designed as mirror contacts so that a current can flow through their main contact when it is closed. At the same time, the switch position is monitored by the monitoring contact being monitored by the monitoring circuit, in particular the position of the monitoring contact. By monitoring the monitoring contact, it is possible to check the corresponding position of the main contact of the contact switch designed as a mirror contact, since the main contact and the monitoring contact are mechanically coupled to one another.In other words, this ensures that the main contact, designed as a relay, has actually reached the required opening distance to ensure the desired galvanic isolation, since only then is the monitoring contact in the closed position, which is detected accordingly by the monitoring circuit. This would allow, among other things, detection of unwanted welding or sticking of the main contact, allowing appropriate measures to be taken.

[0010] Furthermore, according to the invention, faulty control of one of the contact switches can be detected, for example, caused by a problem with the (control) electronics and / or a software problem. Such a detection is particularly relevant during a charging process.

[0011] Furthermore, this type of monitoring allows the position of the contact switches, especially the position of the main contacts, to be monitored when the contact switches are in the non-conductive position, i.e., when the main contact is open. This corresponds to the intended position of the power contacts, which are not contacted when the conductive connection is established. With other monitoring systems, however, only the closed position can be monitored, as a corresponding signal path or current flow is required, which is evaluated to detect an incorrect position.

[0012] Of course, the monitoring circuit can also monitor the respective switching positions of the contact switches that are contacted by the vehicle contact unit. As explained above, due to the mechanical coupling, this will also be done via the associated monitoring contact of the contact switches, which will then be in the open position because the associated main contact is in the closed position.

[0013] The ground contact unit can be placed on a road surface or embedded into it. Accordingly, the ground contact unit is also referred to as a "pad."

[0014] The multiple contacts arranged on the charging surface of the base body of the ground contact unit can be of different types. In each case, the contacts include power contacts, which are necessary for the charging process, as the charging current is conducted via the power contacts. The power contacts are contacts assigned to a neutral potential position ("neutral") or a specific phase. Up to three phases (P1, P2, P3) or even more phases can be provided. The assignment of the respective potential position to the power contacts can also be varied, so that the potential position can be switched.

[0015] In addition to the power contacts, the plurality of contacts may also have at least one control contact (CP contact) via which a control signal is passed in order to determine contact of the ground contact unit during a contact check, in particular the actual contact area of ​​the loading area by the vehicle contact unit.

[0016] Alternatively or additionally, the contacts can have at least one protective conductor contact in addition to the power contacts. In principle, several protective conductor contacts can be provided, each formed separately. Alternatively, the entire charging surface can also be designed as a protective conductor plane through which the power contacts and, optionally, the control contacts extend, with the other types of contacts being electrically insulated from the protective conductor plane by means of an annular insulating region.

[0017] The loading area of ​​the base body is an exposed loading area provided the ground contact unit is prepared for the charging process. This means that the loading area can generally be exposed. It can also be provided that a cover temporarily conceals the loading area when not in use, with the cover being removed manually or automatically to expose the loading area so that charging can take place. In any case, the contacts are arranged on the outside of the loading area so that they are freely accessible provided the optional cover has been removed. This is why the loading area is also referred to as an exposed loading area, as the state assumed is that which exists when a charging process is taking place or shortly before it.

[0018] The monitoring circuit of the charging infrastructure can be fully integrated into the ground contact unit itself, so that the entire monitoring is performed in the ground contact unit. Alternatively, the monitoring circuit can consist of several subcircuits located in the ground contact unit and in at least one separately formed monitoring unit, thereby forming a two- or multi-part monitoring circuit. Likewise, the monitoring circuit of the charging infrastructure can be located entirely outside the ground contact unit.

[0019] The shutdown device, which can be controlled by the monitoring circuit, is activated in particular when the monitoring circuit detects an incorrect position of at least one of the contact switches, i.e. when one of the main contacts is in a closed position although it should be in the open position, since the main contact belongs to a contact switch assigned to a power contact that is not contacted when the conductive connection is present. The shutdown device can then switch off at least the ground contact unit or the entire charging infrastructure, so that a freely accessible power contact, i.e. a non-contacted power contact, is not inadvertently assigned to a potential position, i.e. a voltage is present. The shutdown device can therefore be designed such that an existing potential is completely switched off.Alternatively, the shutdown device can also lower the potential to a non-critical level, which also corresponds to a shutdown within the meaning of the invention, since no charging current flows. This means that the shutdown device does not necessarily have to completely (galvanically) isolate the ground contact unit. In any case, contact protection is guaranteed. The main contact and / or the monitoring contact of the contact switch can be a switch that has an open and a closed position.

[0020] In this respect, the main contact or the monitoring contact is designed as an on / off switch. This means that the main contact or the monitoring contact can be adjusted between an open position and a closed position. One of the advantages of having the main contact as a switch with an open position and a closed position is that the main contact cannot weld when it opens and changes from its closed position, in which the charging current flows through the main contact, to a second position that does not correspond to an open position but to a closed position with a different counterpart, for example ground. An arc can be created when it opens and this would then cause the main contact to weld in the second (closed) position, meaning that the main contact and thus the entire contact switch can no longer be adjusted.This is effectively prevented if at least the main contact is designed as a switch that has an open position and a closed position.

[0021] However, it can also be provided that the main contact and / or the monitoring contact can be switched back and forth between two or more different closed positions.

[0022] In any case, the main contact and the monitoring contact are galvanically isolated from each other, so that a common (closed) circuit is not formed across the two contacts, i.e., the main contact and the monitoring contact. Therefore, the two contacts are not used to provide charging functionality in one switching position of the contact switch and sensor functionality or similar in the other switching position. Rather, the main contact and the monitoring contact are assigned to two independent circuits that are galvanically isolated from each other.

[0023] Monitoring can generally occur during the charging process, but also before and / or after a charging process, particularly in connection with a self-test. Furthermore, monitoring can occur at cyclical intervals.

[0024] If an incorrect or faulty switch position is detected, a warning can be issued, for example, a visual warning, an acoustic warning, and / or a warning via a remote contact. It can also be specified that charging is not possible, i.e., no charging process can be started, if an incorrect or faulty switch position is detected during the check.

[0025] One aspect provides for the contact switches to be designed in such a way that the switching positions of the main contact and the monitoring contact are mutually dependent. This is also referred to as the changeover principle, which is characteristic of a mirror contact. As soon as the main contact moves from the open position to the closed position, the monitoring contact simultaneously moves from the closed to the open position, so that the two positions of the main contact and the monitoring contact are mutually dependent. Due to the mechanical coupling of the main contact and the monitoring contact, it is ensured that the main contact and the monitoring contact cannot be in the open or closed position at the same time. This ensures reliable monitoring of the contact switch and thus of the main contact, which is live when closed.

[0026] In addition, the mechanical coupling is such that the monitoring contact is only closed when the main contact, which is designed as a relay, is sufficiently open, i.e. the isolating distance is present.

[0027] Another aspect provides for the main contact to be configured as a normally open (NO) contact, and the monitoring contact as a normally closed (NC) contact. This means that the contact switch has an initial position in which no current can flow through the main contact, which is configured as a relay, because the main contact is configured as an NO contact. At the same time, the monitoring contact is closed in its initial position, so that the monitoring circuit can determine that a monitoring current or a monitoring signal can flow through the corresponding monitoring contact because there is no interruption.

[0028] According to a further aspect, the monitoring circuit triggers the shutdown device to change its state if the monitoring circuit detects at least one incorrect switching position of the monitoring contacts of the contact switches. Thus, as soon as just one monitoring contact of the contact switches assumes an incorrect or undefined switching position, the monitoring circuit triggers the shutdown device to change its state. This can involve switching off the ground contact unit or the entire charging infrastructure. However, it can also be provided that the power is reduced to a non-critical level. In this respect, the shutdown device can be a power control that is controlled accordingly by the monitoring circuit.

[0029] In particular, the incorrect switching position of the monitoring contact corresponds to the open switching position of the monitoring contact. The open switching position of the monitoring contact results in the main contact coupled to the corresponding monitoring contact being closed, allowing a current to flow via the contact switch to the power contact. This would mean that the associated power contact is at a corresponding potential, which is undesirable in an incorrect switching position. For this reason, the open switching position of the monitoring contact, which corresponds to the closed switching position of the associated main contact, corresponds to the incorrect switching position.

[0030] According to one embodiment, the shutdown device comprises a main switch. The main switch can also be referred to as a contactor, which ensures galvanic isolation when it is opened, in particular, whereby all power contacts are galvanically isolated and not just the power contact whose associated contact switch has an incorrect switching position, which has been detected accordingly. Thus, if the monitoring circuit detects an incorrect or undefined switching position, the shutdown device comprising the main switch can perform galvanic isolation, thereby switching all power contacts to a potential-free state.

[0031] In particular, the monitoring circuit is configured to open the main switch to establish galvanic isolation via the main switch. This ensures a particularly high level of safety, as all power contacts are simultaneously switched to potential-free mode, ensuring complete contact protection. Any charging process would be interrupted.

[0032] According to a further embodiment, the shutdown device can comprise an electronic power control. The electronic power control is designed to regulate the corresponding potential down to a non-critical level, so that contact is possible. In other words, the monitoring circuit can be configured to control the electronic power control to limit the applied voltage to a non-critical value. The non-critical value can be a voltage that is safe, in particular a voltage below 25 V AC, i.e., 25 V AC, or 60 V DC.

[0033] The monitoring circuit can comprise at least a first subcircuit that is integrated into the ground contact unit, wherein the first subcircuit outputs at least one output signal from the ground contact unit to a second subcircuit that is provided in a monitoring unit that is designed separately from the ground contact unit. This results in a functional separation of the monitoring, since the monitoring circuit comprises multiple subcircuits. The at least one output signal can be a single output signal, wherein the ground contact unit transmits its status to the separately designed monitoring unit. The status of the ground contact unit can be a binary signal that corresponds, for example, to the states "okay" or "not okay".The monitoring unit, in particular the second subcircuit, is accordingly configured to evaluate this output signal from the ground contact unit and initiate measures, namely, to activate the shutdown device accordingly. Furthermore, it can also be provided that the first subcircuit transmits multiple output signals, in particular one output signal for each monitored contact switch. The multiple output signals are then evaluated by the separately designed monitoring unit, which is provided, for example, on a server or a computing unit with higher computing power.

[0034] In particular, the second subcircuit of the monitoring circuit is configured to control the shutdown device. Depending on the at least one output signal that the second subcircuit receives from the first subcircuit, the second subcircuit can subsequently control the shutdown device after the second subcircuit has evaluated the at least one output signal.

[0035] The shutdown device can in particular be part of a higher-level system, for example in the case of a parking garage or a building system such as a power supply system.

[0036] In addition, each contact switch can be assigned a control circuit, via which the contact switch is controlled accordingly. The control circuit can comprise a coil driver, which is particularly designed to be redundant. This means that the coil driver has at least one coil with a first coil end and a second coil end. The two coil ends can be connected to an associated driver circuit, in particular a high-side driver and a low-side driver. This ensures that control is possible even if one of the drivers fails.

[0037] Further advantages and features of the invention will become apparent from the following description and the drawings, to which reference is made. In the drawings:

[0038] Figure 1 is a schematic overview of a vehicle battery charging system comprising an electrical charging infrastructure according to the invention and a vehicle with a vehicle contact unit,

[0039] Figure 2 is a schematic plan view of a ground contact unit of an electrical charging infrastructure according to the invention, Figure 3 is a schematic representation of the electrical wiring of the power contacts of the ground contact unit according to Figure 2, and

[0040] Figure 4 is a schematic overview of a process comprising a method for checking a ground contact unit of an electrical charging infrastructure.

[0041] Figure 1 shows a vehicle battery charging system 10, which includes an electrical charging infrastructure 12 and an at least partially electrically powered vehicle 14, which has a vehicle contact unit 16 that can establish a conductive connection with a ground contact unit 18 of the electrical charging infrastructure 12 in order to charge a battery of the vehicle 14 (not shown in detail here).

[0042] The electrical charging infrastructure 12 has a monitoring circuit 20 and a shutdown device 22, which can be fully integrated into the ground contact unit 18. Alternatively, the monitoring circuit 20 can be arranged partially in the ground contact unit 18 and partially in a monitoring unit 24 that is designed separately from the ground contact unit 18. Furthermore, it can be provided that the monitoring circuit 20 and the shutdown device 22 are both arranged entirely in the separately designed monitoring unit 24.

[0043] The separately formed monitoring unit 24 is therefore optional, which is why it is shown in dashed lines in Figure 1. Likewise, the monitoring circuit 20 and the shutdown device 22 are shown in dashed lines, since their respective positions may vary depending on the design.

[0044] In any case, the separately formed monitoring unit 24 would be electrically connected to the ground contact unit 18, as indicated in Figure 1.

[0045] In this respect, the electric charging infrastructure 12 comprises a verification system 25 with which checks can be carried out, as will be explained below.

[0046] Figure 2 shows a plan view of the ground contact unit 18 according to one embodiment. The ground contact unit 18 comprises a plate-shaped base body 26 having a loading surface 28 that is exposed prior to the establishment of the conductive connection. In other words, the loading surface 28 is thus an exposed loading surface when contact is established between the ground contact unit 18 and the vehicle contact unit 16.

[0047] However, the loading area 28 can generally be covered by a cover (not shown here) when not in use, thus protecting the loading area 28 from environmental influences. The corresponding cover can be removed manually or automatically, making the loading area 28 freely accessible.

[0048] Several contacts 30 are provided on the charging surface 28, which may be different contact types.

[0049] In any case, the contacts 30 include, among other things, power contacts 32, which are used for charging the battery of the vehicle 14 by assigning the corresponding power contacts 32 to a potential level 34.

[0050] In the embodiment shown, the ground contact unit 18 is designed as a three-phase ground contact unit, which means that the individual power contacts 32 can be assigned to the phases L1, L2, and L3 as well as a neutral phase N, also referred to as the neutral conductor. These are therefore the corresponding potential levels N, P1, P2, and P3.

[0051] In addition to the power contacts 32, the contacts 30 comprise at least one protective conductor contact 35, i.e. a PE contact, wherein in the embodiment shown, several protective conductor contacts 35 are provided, which are arranged separately and insulated from the power contacts 32 on the charging surface 28.

[0052] As an alternative to the embodiment shown in Figure 2, the ground contact unit 18 can have a continuous protective conductor layer, which thus essentially corresponds to the area of ​​the base body 26 or the base area of ​​the loading area 28. The individual power contacts 32 can then penetrate the corresponding protective conductor layer, with the power contacts 32 each being insulated from the protective conductor layer, for example, by annular sections. Furthermore, the contacts 30 can also include at least one control contact 36, which is used to perform a contact check.

[0053] In the illustrated embodiment, several control contacts 36 are provided, which are shown only as examples. The control contacts 36 can generally be used to determine whether the vehicle contact unit 16 has contacted the ground contact unit 18.

[0054] In particular, the contacts 30 are generally distributed on the loading surface 28 and arranged relative to one another in such a way that at least two control contacts 36 are located in a contact area of ​​the loading surface 28, which is covered by the vehicle contact unit 16 when the conductive connection is established. The two control contacts 36 in the contact area also make it possible to determine the orientation in which the ground contact unit 18 has been contacted.

[0055] By knowing the geometry of the vehicle contact unit 16, it is also possible to determine which contacts 30 have been contacted, i.e. which of the contacts 30 belongs to the subset of the contacted contacts 30 that are located in the contact area of ​​the loading area 28.

[0056] Figure 3 also shows that the power contacts 32, which are assigned to the four different potential positions, namely the phases L1, L2, L3 and the neutral phase N, are each assigned to the corresponding potential position 34 via a contact switch 38.

[0057] The contact switches 38 are therefore connected in series with the power contacts 32, as can be seen from Figure 3.

[0058] The contact switches 38 are each designed as mirror contacts, so that the contact switches 38 have a main contact 40 and a monitoring contact 42. Due to the design as mirror contacts, it is ensured that the main contact 40, which functions as a relay, is mechanically coupled to the monitoring contact 42, so that the respective switching positions of the main contact 40 and the monitoring contact 42 are mutually dependent or interdependent. However, the main contact 40 and the monitoring contact 42 are galvanically isolated from each other, so that both contacts 40, 42 are not assigned to a common circuit. Rather, both contacts 40, 42 are assigned to different circuits that are independent of each other and also galvanically isolated from each other.

[0059] In this respect, there is no switching position of the contact switch 38 in which a closed circuit is formed in which both the main contact 40 and the monitoring contact 42 are integrated, so that a current could flow via both contacts 40, 42 of the contact switch 38.

[0060] The main contact 40 is, as shown in Figure 3, designed as a normally open contact, i.e. an NO contact, whereas the monitoring contact 42 is designed as a normally closed contact, i.e. an NC contact.

[0061] Figure 3 therefore shows the initial position of the contact switches 38, since the contact switches 38 are each in a corresponding switching position in which the main contacts 40 are open, so that no current flow to the power contacts 32 is possible. In other words, the power contacts 32 are not connected to any potential layer 34, thus ensuring contact protection.

[0062] The corresponding contact protection can be monitored by means of the charging infrastructure 12 in that the monitoring circuit 20 monitors, among other things, the respective switching position of the monitoring contacts 42 of the corresponding contact switches 38.

[0063] The monitoring takes place at least at the contact switches 38 which are assigned to power contacts 32 which are not contacted when the conductive connection between the ground contact unit 18 and the vehicle contact unit 16 is present, i.e. at power contacts 32 which do not belong to the subset of the plurality of contacts 30 of the ground contact unit 18 which are contacted.

[0064] The monitoring circuit 20 controls the shutdown device 22 if the monitoring circuit 20 detects that an incorrect switching position exists for one of the monitoring contacts 42, which results in one of the main contacts 40 also having an incorrect switching position, since the monitoring contacts 42 and the main contacts 40 are mechanically coupled to one another.

[0065] The incorrect switching position corresponds to an open switching position of the monitoring contact 42, which is accompanied by a closed switching position of the associated main contact 40, which would mean that a freely accessible power contact 32 would be assigned to a potential position 34, although this is not desired since the corresponding power contact 32 is exposed.

[0066] The shutdown device 22 changes its state due to the control by the monitoring circuit 20, which can be accompanied by a complete shutdown or complete disconnection. In other words, the shutdown device 22 can be designed such that a galvanic isolation of all power contacts 32 is performed, whereby all power contacts 32 would be switched to a potential-free state.

[0067] In this respect, the shutdown device 22 can comprise a main switch 44 or a contactor, which carries out the corresponding galvanic isolation.

[0068] If the shutdown device 22 is integrated in the ground contact unit 18, two switching elements are provided in a current path within the ground contact unit 18, which are connected in series, namely the respective contact switches 38 and the main switch 44.

[0069] Alternatively, the shutdown device 22 can comprise an electronic power control 46, which is designed to reduce the voltage associated with the potential level 34 accordingly, so that the applied voltage is limited to a non-critical value, thereby ensuring contact protection. In other words, the voltage applied to the respective power contact 32, which is coupled to the incorrectly closed main contact 40 of the contact switch 38, is so low that no danger exists.

[0070] Figure 1 already shows that both the monitoring circuit 20 and the shutdown device 22 can be arranged partially in the ground contact unit 18 and partially in the separately formed monitoring unit 24. If the monitoring circuit 20 comprises two subcircuits, it can be provided that the first subcircuit is integrated in the ground contact unit 18 and outputs at least one output signal from the ground contact unit 18 to the second subcircuit of the monitoring circuit 20, which is integrated in the separately formed monitoring unit 24.

[0071] The at least one output signal can transmit the state of the entire ground contact unit 18, for example in the form of a binary signal, i.e. "ok" or "not ok", whereby the monitoring circuit 20, in particular the second subcircuit, then controls the shutdown device 22 accordingly, so that the shutdown device 22 changes its state.

[0072] With the help of the monitoring circuit 20, a continuous touch protection monitoring of the power contacts 32 takes place by continuously monitoring the switching positions of the contact switches 38 which are assigned to power contacts 32 that do not belong to the subset of the contacted contacts 30.

[0073] In addition to this continuous touch protection monitoring, it can further be provided that continuous touch protection monitoring is carried out by continuously monitoring an existing contact of at least one contact 30 that belongs to the subset of contacted contacts 30. This can be the control contact 36, a power contact 32 and / or one of the protective conductor contacts 35.

[0074] For the corresponding monitoring, a signal, for example a high-frequency signal, can be fed in via one of the corresponding contacts 30, wherein an interruption of the corresponding signal would be detected if the conductive connection breaks.

[0075] In this way, faulty activation of one of the contact switches 38 can be detected, for example, caused by a problem with the (control) electronics and / or a software problem. Such detection or monitoring is particularly possible during a charging process. Figure 4 also shows that, in addition to continuous touch protection monitoring, further checks are performed, particularly before a charging process is initiated.

[0076] To prepare for the charging process, a self-test of the power contacts 32 can first be performed to ensure that the contact switches 38 of all power contacts 32 are open. This can be performed at the beginning to ensure that the ground contact unit 18 is fundamentally in a state to be able to carry out a charging process at all.

[0077] For this purpose, the positions of the contact switches 38, in particular the monitoring contacts 42, can be monitored by means of the monitoring circuit 20, as already described above with regard to the continuous contact protection monitoring.

[0078] In addition, the preparation phase includes a compatibility check, during which communication takes place between the ground contact unit 18 and the vehicle contact unit 16 to determine whether the two contact units 16, 18 can even perform a charging process with each other. Corresponding signals can be exchanged to determine whether the contact units 16, 18 are compatible with each other.

[0079] Subsequently, during the preparation phase, positioning can be performed, in which the vehicle 14 is positioned via the ground contact unit 18 or relative thereto, for example, by displaying appropriate signals to a driver of the vehicle 14 so that the driver parks the vehicle 14 as precisely as possible via the ground contact unit 18, thereby establishing a conductive connection. This makes it possible to minimize the size of the ground contact unit 18.

[0080] The vehicle 14 or the vehicle contact unit 16 will then send a charging request to the electrical charging infrastructure 12, in particular the ground contact unit 18. The electrical charging infrastructure 12 processes the charging request accordingly. If the result is positive, this is communicated to the vehicle 14 or the vehicle contact unit 16, whereupon the charging process can be initiated.

[0081] For this purpose, the conductive connection between the vehicle contact unit 16 and the ground contact unit 18 is first established by moving at least one component of the vehicle contact unit 16 in the direction of the ground contact unit 18, whereby it comes into contact with the loading surface 28 of the ground contact unit 18 in some areas, so that at least a subset of the plurality of contacts 30 of the ground contact unit 18 is contacted.

[0082] To determine this, the contact check is performed, which determines whether contacts 30 of the ground contact unit 18 are contacted. Furthermore, it can be determined which of the corresponding contacts 30 are contacted by switching them through individually and / or in groups.

[0083] For this purpose, high-frequency signals can be provided, which are routed via the power contacts 32. Alternatively, this can be done via the control contacts 36. The control contacts 36 can carry different signals, which, in addition to simply determining which contacts 30 are occupied, also allows the contact orientation of the vehicle contact unit 16 with respect to the ground contact unit 18 to be determined.

[0084] Depending on the contact check carried out, the power contacts 32 could then be assigned to specific potential levels 34.

[0085] However, during the testing phase, a protective conductor test is also carried out, in which a test current is passed through at least one contact 30 of the plurality of contacts 30 in order to determine the contact quality of the existing conductive connection between the vehicle contact unit 16 and the ground contact unit 18.

[0086] For this purpose, the vehicle 14 can comprise a current generator or a signal generator that provides the test current, which is conducted via one of the contacts of the vehicle contact unit to a contact 30 of the contacts 30 of the ground contact unit 18 coupled thereto. For example, one of the power contacts 32 can be used, which is coupled to a corresponding power contact of the vehicle contact unit 16, wherein the corresponding power contact 32 of the ground contact unit 18 has been switched to the protective conductor level, which corresponds to the level of the protective conductor contact 35. For this purpose, a relay can be provided, via which the corresponding contact 30 is connected to the protective conductor level.

[0087] A resistance can then be measured to determine the contact quality. The measured resistance should not exceed 0.1 Ω, thus providing a protective conductor resistance threshold of 0.1 Ω. The test current used should be at least 200 mA.

[0088] Alternatively, it can also be provided that the test current is provided by the ground contact unit 18.

[0089] A further step provides for an insulation test to be carried out during the inspection to determine that there are no leakage currents or the like between contacts 30 or other areas of the ground contact unit 18.

[0090] The insulation test can generally be performed between two contacts 30 by applying a test voltage and measuring an insulation resistance, which is compared to a specified insulation resistance threshold. For example, the test voltage is at least 500 V. The insulation resistance threshold is, for example, 0.25 MΩ.

[0091] The two contacts 30 used for the insulation test can be adjacent contacts on the charging surface 28, in particular two contacts 30 of the subset of contacts 30 that are contacted when the conductive connection is present. An (unintentional) conductive connection is most likely to occur between adjacent contacts 30, for example, via an object, dirt, or moisture. In particular, the insulation test is performed between two power contacts 32. Alternatively or additionally, it can be provided that the insulation test is performed between at least one line contact 32 and the at least one protective conductor contact 35. The insulation test can also be performed between at least one line contact 32 and the control contact 35.

[0092] During the insulation test, the insulation can also be measured from a contact 30 of the subset to a point on the loading surface 28 of the base body 26.

[0093] In principle, it can be provided that the insulation test is only carried out if it has previously been determined that at least a subset of the plurality of contacts 30 is actually contacted, i.e. that a conductive connection exists.

[0094] Furthermore, the protective conductor test can also only be performed if it has previously been determined that a conductive connection exists, i.e., at least a subset of the multiple contacts 30 is contacted. Furthermore, the protective conductor test can also only be performed if the insulation test has previously been successfully performed.

[0095] Once the verification has been performed and all verification steps have been successfully completed, the charging process can begin.

[0096] As previously explained, the power contacts 32, which do not belong to the subset of the contacted contacts 30, have already been switched to potential-free state, which was also checked during the self-test during preparation.

[0097] In this respect, only the power contacts 32 of the corresponding potential level 34 are connected, which belong to the subset of the contacted contacts 30.

[0098] A charging current then flows from the ground contact unit 18 into the battery of the vehicle 14 via the vehicle contact unit 16, which has formed a conductive connection with the ground contact unit 18, thereby charging the battery accordingly. Continuous contact protection monitoring takes place during the charging process, as already explained. This determines whether only the contacted power contacts 32 of a corresponding potential level 34 are actually connected, or whether the existing contact is not interrupted during the charging process, by continuously monitoring a contact 30 of the subset of contacted contacts, for example, the control contact 36.

[0099] If it is determined that the contact protection is no longer guaranteed, the shutdown device 22 is activated by the monitoring circuit 20, which either opens the main switch 44 to provide galvanic isolation and / or the electronic power control 46 reduces the corresponding potential until a non-critical voltage value is reached. The non-critical value can be a voltage that is safe, in particular a voltage below 25 V AC (i.e., 25 V AC) or 60 V DC (i.e., 60 V DC).

[0100] After the charging process has been completed, the conductive connection between the vehicle contact unit 16 and the ground contact unit 18 is separated.

[0101] To do this, the previously connected power contacts 32 belonging to the subset are first switched to potential-free mode by controlling the corresponding contact switches 38. Furthermore, the shutdown device 22 can also be controlled accordingly, for example, to implement galvanic isolation via the main switch 44. This creates redundancy. In addition, it can be checked again whether the power contacts 32 are all potential-free by monitoring the associated monitoring contacts 42 via the monitoring circuit 20.

[0102] The conductive connection is then released by disengaging the vehicle contact unit 16 so that there is no longer any contact with the ground contact unit 18. The vehicle 14 can then leave the electrical charging infrastructure 12.

[0103] Finally, a further self-test can be carried out by determining whether all power contacts 32 are in their potential-free state, i.e. whether the associated contact switches 38 are all in the non-current-carrying state, which occurs when the corresponding main contacts 40 are open or the monitoring contacts 42 are closed.

[0104] In principle, the self-test can of course also be performed at other times. Self-tests can therefore be performed at multiple times, for example, cyclically, to continuously check the readiness of the electric charging infrastructure 12, in particular that of the ground contact unit 18.

[0105] This ensures that the vehicle 14 can be efficiently electrically charged by establishing a conductive connection. At the same time, appropriate safety precautions are taken by checking whether the ground contact unit 18 is in a condition suitable for a charging process.

[0106] The sequence shown in Figure 4 and the associated method can in principle be carried out by the electrical charging infrastructure 12, which is set up accordingly.

Claims

Patent claims 1. Electrical charging infrastructure (12) for establishing a conductive connection to a vehicle contact unit (16), wherein the charging infrastructure (12) comprises a ground contact unit (18) having a plate-shaped base body (26) and several contacts (30) arranged on a loading surface (28) of the base body (26) against which the vehicle contact unit (16) can come into contact, wherein the several contacts (30) comprise at least power contacts (32) which are assigned to at least one potential level, wherein the power contacts (32) are each connected in series to a contact switch (38), wherein the contact switches (38) are each designed as mirror contacts, such that each contact switch (38) comprises a main contact (40) and a monitoring contact (42) which are mechanically coupled but galvanically isolated from each other, wherein the charging infrastructure (12) comprises a monitoring circuit (20) which is configured toat least to monitor the respective switching position of the monitoring contacts (42) of the contact switches (38) which are assigned to the power contacts (32) which are not contacted when a conductive connection is present, and wherein the monitoring circuit (20) is configured to control a shutdown device (22).

2. Electric charging infrastructure according to claim 1, characterized in that the contact switches (38) are designed such that the switching positions of the main contact (40) and the monitoring contact (42) are mutually dependent.

3. Electric charging infrastructure according to claim 1 or 2, characterized in that the main contact (40) is designed as a NO contact and the monitoring contact (42) as an NC contact.

4. Electric charging infrastructure according to one of the preceding claims, characterized in that the monitoring circuit (20) controls the shutdown device (22) to change its state when the monitoring circuit (20) detects at least one incorrect switching position of the monitoring contacts (42) of the contact switches (38).

5. Electric charging infrastructure according to claim 4, characterized in that the incorrect switching position of the monitoring contact (42) corresponds to the open switching position of the monitoring contact (42).

6. Electric charging infrastructure according to one of the preceding claims, characterized in that the shutdown device (22) comprises a main switch (40).

7. Electric charging infrastructure according to claim 6, characterized in that the monitoring circuit (20) is configured to open the main switch (40) in order to establish galvanic isolation via the main switch (40).

8. Electric charging infrastructure according to one of the preceding claims, characterized in that the shutdown device (22) comprises an electronic power control (46).

9. Electric charging infrastructure according to claim 8, characterized in that the monitoring circuit (20) is configured to control the electronic power control to limit the applied voltage to a non-critical value.

10. Electric charging infrastructure according to one of the preceding claims, characterized in that the monitoring circuit (20) comprises at least a first sub-circuit which is integrated in the ground contact unit (18), wherein the first sub-circuit outputs at least one output signal from the ground contact unit (18) to a second sub-circuit which is provided in a monitoring unit (24) which is designed separately from the ground contact unit (18).

11. Electric charging infrastructure according to claim 10, characterized in that the second sub-circuit of the monitoring circuit (20) is configured to control the shutdown device (22).

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