Method for testing a ground contact unit, and electric charging infrastructure

Abstract

The invention relates to a method for testing a ground contact unit (12) of an electric charging infrastructure (12). The ground contact unit (18) has a plate-like main body (26) and a plurality of contacts (30) which are arranged on a charging surface (18) of the main body (26), it being possible for a vehicle contact unit (16) to come into contact with the charging surface. The method comprises the following steps: - carrying out a contacting test in order to establish whether at least a subset of the plurality of contacts (30) of the ground contact unit (18) are contacted, - carrying out a protective conductor test in order to determine a contact quality, by way of a test current being conducted across at least one contact (30) of the plurality of contacts (30), and - carrying out continuous touch-protection monitoring of the contacts (30), by way of switching positions of the contact switches (38) that are associated with power contacts (32) which do not belong to the subset of contacted contacts (30) being continuously monitored, and / or by way of existing contacting of at least one contact (30) that belongs to the subset of contacted contacts (30) being continuously monitored and / or by way of a voltage measurement being carried out across at least one of the contacts (30). An electric charging infrastructure (12) is also described.

Description

[0001] Easelink GmbH

[0002] Procedure for checking a ground contact unit and electrical charging infrastructure

[0003] The invention relates to a method for testing a ground contact unit of an electrical charging infrastructure. Furthermore, the invention relates to an electrical charging infrastructure for establishing a conductive connection to a vehicle contact unit.

[0004] 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.

[0005] 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.

[0006] 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 to establish an electrical connection between the ground contact unit and the vehicle contact unit. Depending on the contact point of the vehicle contact unit's connector, the correspondingly occupied contact areas of the ground contact unit are activated to establish the electrical connection via these contact areas.

[0007] Typically, the occupied contact areas are connected using separate relays assigned to each power contact of the ground contact unit. This creates a so-called matrix relay, which, among other things, ensures the safety-relevant requirements regarding the insulation distance of the individual switches. Regardless of the relay positions, however, there are other aspects to consider to enable a charging process.

[0008] The task is to check the ground contact unit of the electric charging infrastructure for its readiness in a cost-effective and efficient manner.

[0009] The object is achieved according to the invention by a method for testing a ground contact unit of an electrical charging infrastructure, wherein the ground contact unit comprises a plate-shaped base body and a plurality of contacts arranged on a charging surface of the base body, against which a vehicle contact unit can be placed. The plurality of contacts comprise at least one protective conductor contact and power contacts, which are assigned to at least one potential layer via at least one contact switch. The method further comprises the steps:

[0010] Performing a contact check to determine whether at least a subset of the plurality of contacts of the ground contact unit is contacted,

[0011] Performing a protective conductor test to determine a contact quality by passing a test current through at least one contact of the plurality of contacts, and

[0012] Carrying out continuous contact protection monitoring of the contacts by continuously monitoring the switching positions of the contact switches assigned to power contacts that do not belong to the subset of contacted contacts and / or by continuously monitoring an existing contact of at least one contact that belongs to the subset of contacted contacts and / or by carrying out a voltage measurement on at least one of the contacts.

[0013] Furthermore, 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 comprises a ground contact unit having 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 be placed. The plurality of contacts comprise at least one protective conductor contact and power contacts, which are assigned to at least one potential layer via at least one contact switch.The charging infrastructure has a testing system that is configured to perform a contact check to determine whether at least a subset of the plurality of contacts of the ground contact unit is contacted, to perform a protective conductor check to determine a contact quality, wherein the testing system is configured to conduct a test current via at least one contact of the plurality of contacts, and to perform continuous contact protection monitoring of the contacts, wherein the testing system is configured to continuously monitor switch positions of the contact switches that are assigned to power contacts that do not belong to the subset of the contacted contacts, and / or to continuously monitor an existing contact of at least one contact that belongs to the subset of the contacted contacts and / or to perform a voltage measurement on at least one of the contacts.

[0014] According to the invention, several checks are performed before a charging current is passed through the power contacts to charge a vehicle that is coupled to the corresponding ground contact unit via its vehicle contact unit. These checks include, among other things, the contact check, which is performed to determine whether the contacts of the ground contact unit are actually connected, i.e., whether a conductive connection to the vehicle contact unit exists. Furthermore, the protective conductor check not only checks continuity but also determines the corresponding contact quality to determine whether the contact meets certain minimum requirements so that a charging process can begin.

[0015] In addition, touch protection monitoring is performed to ensure that unintentional contact with accessible contacts of the ground contact unit is not possible. Touch protection monitoring is performed continuously during conductive charging. However, it can also be configured to be performed immediately before the charging process.

[0016] For this purpose, for example, it is provided that during continuous contact protection monitoring the respective switching positions of the contact switches are monitored. These are the power contacts that are not part of the subset of contacted contacts, which is why they are accessible from the outside. These accessible contacts can also be referred to as exposed contacts, as they are not covered by the vehicle contact unit when the conductive connection is present. By monitoring the switching positions of the contact switches, it is checked whether the corresponding power contacts are switched to a potential-free state, as is intended for the exposed power contacts, i.e. the power contacts that do not form a conductive connection with the vehicle contact unit.

[0017] Alternatively or additionally, continuous touch protection monitoring can consist of continuously monitoring whether the previously established conductive connection is maintained or whether the established conductive connection has been broken. For this purpose, it may be sufficient to check at least one of the contacts in the subset, since this was previously contacted. In principle, the at least one contact in the subset used for continuous touch protection testing can be a power contact or a protective conductor contact of the multiple contacts, provided a corresponding signal is applied and evaluated, for example, a high-frequency signal that is fed in ("HF loop").However, other types of contacts can also be provided which are used for continuous monitoring, for example a control contact via which a corresponding control signal is transmitted which is monitored.

[0018] Continuous touch protection monitoring can be carried out using a monitoring circuit that monitors the switching position of the contact switches and / or the continuous contacting of the corresponding contact of the subset, for example the control signal.

[0019] Alternatively or additionally, a voltage measurement may be performed on at least one contact, in particular on a power contact. This at least one contact may be referred to as a monitored contact.

[0020] A measuring circuit may be provided for this purpose, which is configured to carry out the voltage measurement on the at least one contact.

[0021] In particular, the measuring circuit is designed to detect an impermissible voltage applied to the monitored contact.

[0022] The measuring circuit can be designed as part of the monitoring circuit or separately.

[0023] The measuring circuit can therefore be used to provide protection against contact, as an impermissible voltage would be detected.

[0024] In principle, the ground contact unit can be provided with a continuous surface that forms the protective conductor contact, i.e., provides a so-called protective conductor level, which is, among other things, perforated by the power contacts. In other words, the charging surface is largely formed by the protective conductor contact, with the corresponding power contacts being arranged in the level formed by the protective conductor contact, in particular with an annular insulating area to electrically insulate the power contacts from the protective conductor contact, i.e., the corresponding protective conductor level.

[0025] The protective conductor test is provided to check the contact quality of an established conductive connection by passing a test current through at least one of the contacts. The corresponding test current can be provided by the ground contact unit. Alternatively, it can be provided that a power source of the motor vehicle is used to provide the test current, which is then passed from the vehicle contact unit, which is conductively connected to the ground contact unit, through at least one contact of the ground contact unit. The measurement of the corresponding test current, in particular an associated resistance measurement, in order to determine the contact quality can also be carried out in the ground contact unit itself or in the vehicle, which is electrically connected to the ground contact unit via its vehicle contact unit, provided that the conductive connection between the vehicle contact unit and the ground contact unit exists.

[0026] In particular, the protective conductor check is carried out before a charging process is carried out.

[0027] The checks ensure that the ground contact unit is ready for charging. If the checks have been successfully completed, charging can begin by flowing a charging current through the appropriately switched power contacts of the ground contact unit and the connected vehicle contact unit.

[0028] During the charging process, and optionally before the charging current flows for the first time, the contact protection check can be performed continuously to ensure that the contacts not required for the charging process, especially the accessible power contacts, can be touched and that the continuity of the contacts of the subset, i.e., the contacted contacts, is maintained. In other words, it would be detected if an existing contact between the vehicle contact unit and the ground contact unit breaks during the charging process.

[0029] One aspect provides that the subset of the plurality of contacts is assigned to a contact area of ​​the loading area, which is covered by a component of the vehicle contact unit when a conductive connection is established between the ground contact unit and the vehicle contact unit. The corresponding subset, i.e., the number of the plurality of contacts located in the contact area of ​​the loading area, depends on the size of the ground contact unit and / or the size of the corresponding component of the vehicle contact unit, which interacts with the contacts of the ground contact unit for the conductive connection.

[0030] In an extreme example, it may be intended that all contacts of the ground contact unit are occupied, meaning that there are no exposed contacts in the contacted state. Accordingly, the subset of the multiple contacts can correspond to all contacts of the ground contact unit. Typically, however, the ground contact unit has more contacts than the contacts required for the conductive connection between the ground contact unit and the vehicle contact unit. This ensures, among other things, that the motor vehicle does not have to come to a stop precisely over a specific area of ​​the ground contact unit, thus providing greater flexibility.The component of the vehicle contact unit that covers the contacting area can be a movable part of the vehicle contact unit, for example a movable charging nozzle or the like, which is moved from an underbody of the motor vehicle towards the ground contact unit in order to establish the conductive connection.

[0031] According to another aspect, an insulation test is performed between two contacts by applying a test voltage and measuring an insulation resistance, which is compared to an insulation resistance threshold. The insulation test can also be performed before the charging process begins, thus distinguishing the insulation test from monitoring the charging process using a residual current device. The insulation test is particularly advantageous when the ground contact unit is used in an area exposed to external influences, especially moisture and / or dirt, for example, in an uncovered parking lot.

[0032] For example, the two contacts used in the insulation test are adjacent contacts on the charging surface, in particular two contacts of the subset. The insulation test can therefore be carried out between two contacts that are immediately adjacent to one another, since an (unintentional) conductive connection is most likely to occur between adjacent contacts, for example via an object, dirt, or moisture. In particular, contacts belonging to the subset can be used in the insulation test. In this respect, the insulation is measured between two contacts that are used to form the conductive connection. In particular, the insulation test is carried out between two power contacts. Alternatively, it can be provided that the insulation test is carried out between at least one line contact and the at least one protective conductor contact.

[0033] For example, in the case of a protective conductor level, it can be provided that all power contacts are switched to a common potential, whereby the insulation between the power contacts lying at the common potential is then measured with respect to the protective conductor level.

[0034] In an alternative embodiment, it may be provided that the insulation test is carried out successively for different pairs of contacts in order to ensure that sufficient insulation is provided.

[0035] For example, the test voltage for insulation testing is at least 500 V. The insulation resistance threshold is, for example, 0.25 MΩ.

[0036] Another aspect provides that the insulation test is only performed if it has previously been determined that at least a subset of the multiple contacts is in contact. Thus, the insulation test is only performed if a conductive connection exists between the ground contact unit and the vehicle contact unit. Furthermore, during the insulation test, the insulation can be measured from one of the contacts, in particular a contact of the subset, to a point on the loading area of ​​the base body. This ensures that no current flows beyond the contact area. This ensures adequate contact protection.

[0037] Another aspect stipulates that the protective conductor test is only performed if it has previously been determined that at least a subset of the multiple contacts is contacted. The protective conductor test is therefore also only performed if a conductive connection has previously been detected. In particular, the protective conductor test is only performed if the insulation test has previously been successfully performed. If an insulation fault is detected during the insulation test, the test routine is aborted, so the protective conductor test is not performed at all.

[0038] Another aspect provides for power contacts that are not part of the contacted contacts to be switched to potential-free mode. In particular, the switch positions of the contact switches assigned to the potential-free power contacts are continuously monitored. This ensures touch protection monitoring by ensuring that potential-free power contacts do not inadvertently have a potential intended for the charging process.

[0039] According to a further aspect, a shutdown device is activated if the continuous contact protection monitoring determines that contact protection is not guaranteed. This is particularly the case if at least one of the contact switches assigned to a power contact that does not belong to the subset of contacted contacts is not in the intended switching position. Alternatively or additionally, this is the case if the existing contact of the at least one contact belonging to the subset of contacted contacts has been broken.

[0040] The disconnection device may comprise a main switch, such as a contactor. The main switch can then be opened to create galvanic isolation.

[0041] Alternatively or additionally, the shutdown device may comprise an electronic power control that reduces the applied potential to a non-critical value.

[0042] In other words, activating the shutdown device corresponds to fault protection, as the state of the contact switches is checked. In the event of a fault, the main switch is opened to switch the contacts to a potential-free state and / or the applied potential is reduced in value. Alternatively or additionally, this is done if the existing contact is suddenly interrupted or is not terminated in a controlled manner. According to a further aspect of the invention, the power contacts each have a current path within the ground contact unit, with at least two switching elements assigned to each current path. This creates redundancy, ensuring that in the event of a fault in one of the switching elements, the corresponding power contacts are still switched to a potential-free state.The two switching elements are, in particular, a contact switch for each power contact and a common main switch for all power contacts. As already mentioned, the disconnection device can be activated if the contact protection monitoring detects, for example, that a contact switch is connected in such a way that the connected power contact is assigned to a potential position, even though it should be switched to a potential-free state. This ensures that the corresponding power contacts, which should actually be switched to a potential-free state, can be touched because the corresponding potential has been completely switched off or reduced to a low and non-critical level by the disconnection device.

[0043] In addition, a self-test of the power contacts can be performed to ensure that the contact switches of all power contacts are open. The self-test can be performed, in particular, before the contact check and / or after a charging process has been completed and the contact has been released. In this respect, two or more self-tests can be provided in a charging cycle: namely at the beginning of the charging cycle, before the vehicle contact unit and the ground contact unit form the conductive connection, and after a successful charging process, when the conductive connection has been deliberately released. This ensures that the power contacts or their contact switches are in the correct switching position if no contact is present. The correct position of the corresponding contact switches means that all power contacts are switched to a potential-free state.In principle, the self-test can of course also be carried out at other times.

[0044] Furthermore, the plurality of contacts can comprise at least one control contact, by means of which the contact check is carried out. In particular, the plurality of contacts comprise at least two control contacts, by means of which a contact orientation of the vehicle contact unit is detected. The control contacts can be separately formed contacts of the plurality of contacts, i.e., contacts provided on the loading area in addition to the power contacts and the protective conductor contact. A defined signal can be fed in via the control contacts, which interacts with an associated control contact of the vehicle contact unit, thereby closing an electrical circuit in which the corresponding signal can be evaluated.If two control contacts are provided, which are also supplied with different signals, the orientation of the vehicle contact unit relative to the ground contact unit can be determined if the conductive connection is present, i.e., the contact orientation. Regardless, two control contacts make it possible to create two channels, thus creating corresponding redundancy.

[0045] In principle, instead of the separately designed control contacts, special signals can also be used to perform the contact verification. For example, special signals can be transmitted via the power contacts, which are then evaluated to determine whether a conductive connection exists. These can be high-frequency signals that run along a signal loop that includes the ground contact unit and the vehicle contact unit.

[0046] Another aspect stipulates that the insulation test checks the insulation between at least one control contact and one of the power contacts. Therefore, the insulation between the control contact and neighboring contacts, such as the power contacts, is also checked.

[0047] According to a further aspect, the contact through which the test current is conducted during the protective conductor test is first brought to a protective conductor level to which the protective conductor contact is assigned. The contact is connected to the protective conductor level via a relay. In other words, the contact can be a power contact that can be connected to the protective conductor level, for example ground or earth, via a corresponding relay. The corresponding test current can then be fed in by a power generator, for example a vehicle-mounted power generator, via a contact of the vehicle contact unit coupled to the respective power contact, which then flows into the protective conductor level via the appropriately switched relay. A resistance can then be measured to determine whether the desired contact quality with regard to the conductive connection is present.

[0048] The test current can be at least 200 mA. The resistance measured during the protective conductor test should not exceed 0.1 Ω, so a protective conductor resistance threshold of 0.1 Ω is provided, which is compared with the measured protective conductor resistance to determine the corresponding contact quality.

[0049] In principle, the electric charging infrastructure is designed to carry out a process with the features mentioned above. Therefore, the aforementioned features also represent features of the electric charging infrastructure.

[0050] The respective contact switch can be designed as a mirror contact and have a main contact and a monitoring contact that are mechanically coupled but galvanically isolated from each other.

[0051] The main contact and / or the monitoring contact of the contact switch can be a switch that has an open position and a closed position. 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. The advantage of the main contact being designed as a switch with an open position and a closed position is, among other things, 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.When opened, an arc can be generated, which would then cause the main contact to weld in the second (closed) position, making it impossible to adjust the main contact and thus the entire contact switch. This is effectively prevented if at least the main contact is designed as a switch with an open and a closed position. 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.

[0052] 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.

[0053] 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.

[0054] If a faulty or incorrect 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 a faulty or incorrect switch position is detected during the check.

[0055] For example, the measuring circuit used to perform the voltage measurement at the at least one contact comprises a voltage divider and a comparator to which a reference voltage is applied. The voltage divider can comprise a first resistor (or a first capacitor) and a second resistor (or a second capacitor).

[0056] If two resistors are provided (ohmic voltage divider), they differ in resistance by at least a factor of 10, in particular by a factor of 100. A first resistor can have a resistance of 1 M ohm, whereas a second resistor has a resistance of 10 k ohm. In the voltage divider, the first resistor (or the first capacitor) can be arranged between the monitored contact and a center tap.

[0057] The second resistor, i.e. the one with the smaller resistance value, or the second capacitor is arranged between the center tap and the protective conductor level.

[0058] In this respect, the voltage divider can be a capacitive voltage divider, provided two capacitors are provided. A hybrid voltage divider can also be provided, which, for example, comprises the first resistor and the second capacitor.

[0059] 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:

[0060] 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,

[0061] Figure 2 is a schematic plan view of a ground contact unit of an electrical charging infrastructure according to the invention,

[0062] Figure 3 is a schematic representation of the electrical connection of the power contacts of the ground contact unit according to Figure 2, and

[0063] Figure 4 is a schematic overview of a process comprising a method for checking a ground contact unit of an electrical charging infrastructure.

[0064] Figure 1 shows a vehicle battery charging system 10 comprising an electrical charging infrastructure 12 and an at least partially electrically powered vehicle 14 having 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). 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 completely in the separately designed monitoring unit 24.

[0065] 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.

[0066] In any case, the separately formed monitoring unit 24 would be electrically connected to the ground contact unit 18, as indicated in Figure 1.

[0067] 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.

[0068] In Figure 2, the ground contact unit 18 is shown in a plan view according to an embodiment variant.

[0069] The ground contact unit 18 comprises a plate-shaped base body 26 having a loading surface 28 that is exposed prior to establishing the conductive connection. In other words, the loading surface 28 is an exposed loading surface when contact is established between the ground contact unit 18 and the vehicle contact unit 16.

[0070] 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.

[0071] Several contacts 30 are provided on the charging surface 28, which may be of different contact types. In each 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.

[0072] 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.

[0073] 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.

[0074] As an alternative to the embodiment shown in Figure 2, the ground contact unit 18 can have a continuous protective conductor plane, 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 break through the corresponding protective conductor layer, wherein the power contacts 32 are each insulated from the protective conductor plane, for example, by annular sections.

[0075] In addition, the contacts 30 may also include at least one control contact 36, which is used to perform a contact check.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] The contact switches 38 are therefore connected in series with the power contacts 32, as can be seen from Figure 3.

[0081] 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 dependent on one another. However, the main contact 40 and the monitoring contact 42 are galvanically isolated from one another, 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 one another and also galvanically isolated from one another.

[0082] 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.

[0083] As shown in Figure 3, the main contact 40 is 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. 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.

[0084] 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.

[0085] 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.

[0086] Alternatively or additionally, a measuring circuit 43 may be provided, for example as part of the monitoring circuit 20 and / or the testing system 25. The measuring circuit 43 is configured to perform the voltage measurement on at least one of the contacts 30, in particular on one of the power contacts 32. This contact 30 may therefore also be referred to as a monitored contact.

[0087] Measuring circuit 43 is configured to detect an impermissible voltage applied to the monitored contact. Thus, contact protection can be implemented using measuring circuit 43, since an impermissible voltage would be detected.

[0088] Regardless of the type of detection, the monitoring circuit 20 controls the shutdown device 22 if the monitoring circuit 20 determines that an incorrect switching position is present at one of the monitoring contacts 42 and / or an impermissible voltage is present, 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.

[0089] 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.

[0090] An impermissible voltage corresponds to a voltage that is applied to a freely accessible contact 30.

[0091] 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.

[0092] In this respect, the shutdown device 22 can comprise a main switch 44 or a contactor, which carries out the corresponding galvanic isolation.

[0093] 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.

[0094] 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.

[0095] This can also be verified by the measuring circuit 43 by performing a new voltage measurement at the monitored contact. After adjustment by the electronic power control 46, the measured voltage should now be below a limit value. This ensures contact protection.

[0096] In Figure 1 it was already shown that both the monitoring circuit 20 and the shutdown device 22 can be arranged partly in the ground contact unit 18 and partly in the separately formed monitoring unit 24.

[0097] 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 of the ground contact unit 18 to the second subcircuit of the monitoring circuit 20, which is integrated in the separately formed monitoring unit 24.

[0098] 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.

[0099] With the help of the monitoring circuit 20, 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 contacted contacts 30. Alternatively or additionally, a voltage measurement can be performed on at least one of the contacts 30, in particular on one of the power contacts 32.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] Figure 4 also shows that in addition to the continuous contact protection monitoring, further checks are carried out, in particular before a charging process is initiated.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] Depending on the contact check carried out, the power contacts 32 could then be assigned to specific potential levels 34.

[0113] 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.

[0114] For this purpose, the vehicle 14 can comprise a current generator or a signal generator which provides the test current which is passed 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.

[0115] 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.

[0116] 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.

[0117] Alternatively, it can also be provided that the test current is provided by the ground contact unit 18.

[0118] 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.

[0119] The insulation test can generally be performed between two contacts 30 by applying a test voltage and measuring an insulation resistance, which is then compared to a predetermined insulation resistance threshold. For example, the test voltage is at least 500 V. The insulation resistance threshold is, for example, 0.25 MΩ. 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 in contact 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, the insulation test may be performed between at least one line contact 32 and the at least one protective conductor contact 35. The insulation test may also be performed between at least one line contact 32 and the control contact 35.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] Once the verification has been performed and all verification steps have been successfully completed, the charging process can begin.

[0124] As previously explained, the power contacts 32 that do not belong to the subset of contacted contacts 30 have already been switched to potential-free mode, which was also verified during the self-test during preparation. Therefore, only the power contacts 32 of the corresponding potential level 34 that belong to the subset of contacted contacts 30 are switched on.

[0125] 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 the conductive connection with the ground contact unit 18, whereby the battery is charged accordingly.

[0126] During the charging process, continuous touch protection monitoring takes place, 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, control contact 36.

[0127] If it is determined that the contact protection is no longer guaranteed, the shutdown device 22 is activated by the monitoring circuit 20, whereby either the main switch 44 is opened to establish 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.

[0128] After the charging process has been completed, the conductive connection between the vehicle contact unit 16 and the ground contact unit 18 is separated.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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. Method for checking a ground contact unit (12) of an electric charging infrastructure (12), wherein the ground contact unit (18) has a plate-shaped base body (26) and several contacts (30) arranged on a loading surface (18) of the base body (26) on which a vehicle contact unit (16) can be attached, wherein the several contacts (30) comprise at least one protective conductor contact (35) and power contacts (32) which are assigned to at least one potential level (34) via at least one contact switch (38), wherein the method comprises the following steps: Performing a contact check to determine whether at least a subset of the multiple contacts (30) of the ground contact unit (18) is contacted, Performing a protective conductor test to determine contact quality by passing a test current through at least one contact (30) of the several contacts (30), and Performing continuous touch protection monitoring of the contacts (30) by continuously monitoring the switching positions of the contact switches (38) that are assigned to power contacts (32) that do not belong to the subset of contacted contacts (30), and / or by continuously monitoring an existing contacting of at least one contact (30) that belongs to the subset of contacted contacts (30), and / or by performing a voltage measurement on at least one of the contacts (30).

2. Method according to claim 1, characterized in that the subset of the multiple contacts (30) is assigned to a contacting area of ​​the loading surface (28) which is covered by a component of the vehicle contact unit (16) when a conductive connection is established between the ground contact unit (18) and the vehicle contact unit (16).

3. Method according to claim 1 or 2, characterized in that an insulation test is performed between two contacts (30) by a A test voltage is applied and an insulation resistance is measured, which is then compared to a predetermined insulation resistance threshold.

4. Method according to claim 3, characterized in that the two contacts (30) used in the insulation test are adjacent contacts (30) on the loading surface (28), in particular two contacts (30) of the subset.

5. Method according to claim 3 or 4, characterized in that the insulation check is only carried out if it has previously been established that at least the subset of the multiple contacts (30) is contacted.

6. Method according to one of claims 3 to 5, characterized in that during the insulation test the insulation from one of the contacts (30), in particular a contact (30) of the subset, to a point on the loading surface (28) of the base body (26) is measured.

7. Method according to one of the preceding claims, characterized in that the protective conductor check is only carried out if it has previously been established that at least the subset of the multiple contacts (30) is contacted.

8. Method according to claim 7 insofar as it relates back to claim 3, characterized in that the protective conductor test is only carried out if the insulation test has been successfully carried out beforehand.

9. Method according to one of the preceding claims, characterized in that power contacts (32) that do not belong to the subset of contacted contacts (30) are switched without potential, in particular wherein the respective switching positions of the contact switches (38) that are assigned to the power contacts (32) switched without potential are continuously monitored.

10. Method according to one of the preceding claims, characterized in that a shutdown device (22) is activated if, during continuous touch protection monitoring, it is determined that touch protection is not ensured, in particular if at least one of the contact switches (38) is not in the intended switching position which corresponds to a The power contact (32) is assigned that does not belong to the subset of contacted contacts (30) and / or the existing contacting of at least one contact (30) that belongs to the subset of contacted contacts (30) has been broken off.

11. Method according to one of the preceding claims, characterized in that the power contacts (32) each have a current path within the ground contact unit (18), wherein at least two switching elements are assigned to each current path, in particular a contact switch (38) per power contact (32) and a common main switch (44) for all power contacts (32).

12. Method according to one of the preceding claims, characterized in that a self-test of the power contacts (32) is carried out to ensure that the contact switches (38) of all power contacts (32) are open, in particular wherein the self-test is carried out before the contact check and / or after a charging process and a release of the contact.

13. Method according to one of the preceding claims, characterized in that the multiple contacts (30) comprise at least one control contact (36) by means of which the contact verification is carried out, in particular wherein the multiple contacts (30) comprise at least two control contacts (36) by means of which a contact orientation of the vehicle contact unit (16) is detected.

14. Method according to claim 13 insofar as it relates back to claim 3, characterized in that during the insulation check the insulation between the at least one control contact (36) and one of the power contacts (32) is checked.

15. Method according to one of the preceding claims, characterized in that the contact (30), through which the test current is passed during the protective conductor test, has previously been brought to a protective conductor level to which the protective conductor contact (35) is assigned, in particular wherein the contact (30) is connected to the protective conductor level via a relay.

16. Electrical charging infrastructure for establishing a conductive connection to a vehicle contact unit (14), 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 be connected, wherein the several contacts (30) comprise at least one protective conductor contact (35) and power contacts (32) assigned to at least one potential level (34) via at least one contact switch (38), and wherein the charging infrastructure (12) comprises a verification system (25) configured to perform a contact verification to determine whether at least a subset of the several contacts (30) of the ground contact unit (18) is contacted, and to perform a protective conductor verification to determine contact quality.wherein the testing system (25) is configured to pass a test current through at least one contact (30) of the several contacts (30) and to perform continuous touch protection monitoring of the contacts (30), wherein the testing system (25) is configured to continuously monitor switching positions of the contact switches (28) that are assigned to power contacts (32) that do not belong to the subset of contacted contacts (30), and / or to continuously monitor an existing contacting of at least one contact (30) that belongs to the subset of contacted contacts (30), and / or to perform a voltage measurement on at least one of the contacts (30).

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