Charging system of an electrically powered vehicle and method for operating a charging system

Abstract

The invention relates to a charging system for an electrically powered vehicle (1), with at least one preferably vehicle-side contact pin (10), and a method for operating the charging system.

Description

[0001] The invention relates to a charging system of an electrically powered vehicle according to the preamble of claim 1 and to a method for operating the charging system according to claim 9.

[0002] In such a charging system of an electrically powered vehicle, at least two electrical components (i.e., a contact element and a cooperating mating contact element, or a contact pin and a cooperating contact socket), in particular of a charging system of an electrically powered vehicle, are connectable. By connecting a charging socket installed in the vehicle with the mating contact—i.e., the charging gun—of an external, usually stationary charging station, the vehicle's traction battery is temporarily electrically charged.

[0003] The removable mechanical-physical connection of such electrically conductive connections is usually based on plug contacts. Such plug contacts must produce the highest possible, evenly distributed contact surface pressure and also exhibit flexibility and spring preload to compensate for thermal-mechanical stresses and material settling during operation. Nevertheless, due to statistical variability, wear, aging, contamination, and damage, there is a large, stochastic variation in electrical contact resistance. For example, for plug contacts in CCS2 charging systems, these values ​​can range between 20 µΩ and 80 µΩ, and even higher in cases of severe damage.

[0004] Thus, the contact resistance determines the heat loss generated due to a current flow through the contact and leads to a progressive heating of the contact, the connected electrical conductors and the physical-geometric environment, essentially the charging socket and high-current conductor track installed in the vehicle, the externally connected charging gun and its charging cable.

[0005] In this case, the current-carrying capacity of such an electrical contact is limited by compliance with safe operating temperature limits. These are partly predefined in international standards and, in the example of CCS2 plug contacts, should not exceed 90°C at the hottest point, i.e., directly in the plug contact. It is important to note that this standardized maximum temperature is not a homologation-relevant maximum value, the derivation and definition of which is based on a variety of influences. Technically speaking, the contact temperature can be temporarily exceeded without impairing function or service life.

[0006] What all such plug contacts have in common is that in applications that require an electrical connection between two components (i.e. contact element with cooperating mating contact element) with a high current carrying capacity, as is the case, for example, with high-voltage systems in the automotive sector, compliance with the operating temperature limits is difficult.

[0007] The desired high current densities of the power line and the contact areas lead to high ohmic losses due to the quadratic dependence on the current flow and accordingly to high Joule heat within the conductor material or at electrical contact points, such as plug connections or screw connections.

[0008] An example of extreme stress on a power line and its contacts is the rapid charging of an electric vehicle's traction battery. High-voltage battery systems used in modern electric vehicles will operate at voltages of up to 800 to 1000 V and current loads in the range of approximately up to 1000 A, as well as load intervals of approximately up to ten minutes. The traction battery is electrically connected to a charging socket on the exterior of the vehicle body via busbars or cables.

[0009] This results in increased local heat development, particularly in the area of ​​these electrical contact connections, resulting in a locally significantly increased component temperature, which can lead to damage to the component or other connecting components and thus to a technical failure of the electrical contact.

[0010] The problem of heat loss and its dissipation, particularly in the case of a particularly high-current electrical connection, especially a plug connection, also exists in other areas involving high-performance batteries, such as in the aviation sector and the energy storage and release in photovoltaic systems and wind turbines.

[0011] The dissipation of lost heat and thus the cooling of such an electrical contact area due to a contributing thermal conduction effect is based on the necessity of a temperature gradient, since the lost heat can only flow from areas of higher, local component temperatures to areas with lower, local component temperatures. This heat flow within the component leads to a time-dependent temperature profile, with increasing local component temperatures over time. The adjacent component areas, which progressively heat up due to the heat flow from the contact area, eventually reach a temperature limit beyond which sufficient heat flow from the electrical contact area is no longer guaranteed, and thus the area of ​​the electrical contact geometry heats up beyond permissible limit temperatures unless measures to limit power losses are initiated.

[0012] Typically, temperature sensors are used for this purpose. These sensors are geometrically integrated with a good thermal coupling to the pin or contact pin of the electrical plug-in contact. Their temperature value is read to control a dynamic charging current limiter. When a maximum temperature value slightly below the maximum permissible contact temperature is reached, the charging current is regulated, which leads to a reduction in ohmic losses and thus self-heating of the contact. The current limit can be progressively reduced to zero, i.e., the charging current is completely shut off.

[0013] Fundamentally, the functional principle of heat conduction—that is, the dissipation of the waste heat generated in the contact to a cooler heat sink—is limited by the thermal conductivity of technically available materials, such as copper, as well as the geometric design of the heat-conducting conductor. For example, in vehicle construction, both the material and the geometry of the electrical contacts are specified due to standardized design specifications for rapid charging systems. This results in a significant increase in component temperature, at least in the area of ​​the electrical contacts of a power line within the vehicle.

[0014] A modular connector is known from DE 10 2015 004 808 B3. WO 2021 / 213780 A1 proposes the use of gel-like heat-conducting agents between the contact areas and a heat exchanger to cool the electrical contact areas of a busbar.

[0015] DE 10 2017 129 250 A1 discloses a heat-conducting gap filler between a Joule heat-emitting contact of a busbar and a housing representing a heat sink.

[0016] Furthermore, it is known from US 2021 / 0021077 A1 to surround an electrical connection to be cooled with a housing that is filled with phase change material such as paraffins or greases.

[0017] DE 10 2018 108 181 A1 discloses a charging coupler with a cooling device. For easy cooling, the charging contacts of the charging coupler are directly surrounded by a phase-change material, and the charging contacts are in contact with the phase-change material. US 2016 / 0 221 458 A1 discloses a vehicle charging connector configured to conductively transmit charging current from an external source to the vehicle in order to charge a traction battery of the vehicle. Furthermore, a cooling system is configured to cool the charging connector depending on the temperature of the charging connector. The cooling system can use coolant and / or air to cool the charging connector.

[0018] What all these solutions have in common is that they are technically complex and may not be sufficient locally in the contact areas to prevent a limit temperature from being exceeded. In particular, the method according to US 2021 / 0021077 A1 is limited in its effectiveness by the fact that heat conduction, for example, from the thermally highly conductive electrical conductor must first take place into an electrically insulating housing part, and from there into the latent heat storage device, i.e., into the phase-change material, which progressively transforms from a solid or amorphous phase state into a liquid state during the heat absorption process.The melting boundary that occurs here is a system boundary that progressively migrates away from the location of heat input and becomes thermally less effective over time with increasing layer thickness of the molten phase, since the progressively growing liquid layer can only transfer heat into the boundary layer to be melted by means of a constantly increasing temperature gradient.

[0019] Based on the cited prior art and the described findings of the inventors, it is a preferred object of the technology according to the invention to reduce or eliminate at least one disadvantage of a previously known solution or to propose an alternative solution.

[0020] In particular, a preferred object of the technology disclosed here is to provide a device for electrically connecting at least two electrical components (i.e., contact pin and contact socket), namely a charging system of an electrically powered vehicle, with a coolable contact area, which device is improved with respect to at least one of the following factors: efficient local heat dissipation, so that a resulting contact temperature is reduced and the robustness and reliability of the contact as well as the specific current carrying capacity are increased, manufacturing time, manufacturing costs, complexity of manufacturing, space utilization, operational reliability, sustainability, strength, overall weight, and / or component reliability. Further preferred objects can arise from the advantageous effects of the technology disclosed here.

[0021] The problem(s) is / are solved by the features of claim 1 or 9. The patent claims dependent thereon represent preferred embodiments.

[0022] According to the invention, a charging system of an electrically operated vehicle is proposed as a device for electrically connecting at least two electrical components (ie contact pin and contact socket), in particular of a charging system of an electrically driven vehicle, to an external charging infrastructure, which has a power line which can be electrically connected via a first connection area to a first electrical component and via a further connection area to a second electrical component by means of a detachable connection device.

[0023] The detachable connecting device includes an electrical contact surface with this connection area. A cooling device is provided to dissipate heat from the contact surface, which, according to the invention, is integrated directly into the electrically conductive connection area.

[0024] This represents a significant technical improvement over the prior art presented in US 2021 / 0021077 A1. In US 2021 / 0021077 A1, cooling of the electrical connection is achieved only through an indirect connection of the thermally active cooling material. Heat conduction into the thermally active phase change material is limited and inefficient, as heat conduction must first occur through housing walls and other geometries before the lost heat can be transferred to the thermally active phase change material. The immediate consequence of this is that, in the existing prior art, a relatively high temperature gradient develops between the conductor material to be cooled and the thermally active phase change material, as heat conduction can only occur indirectly, i.e., through electrically insulating and thus thermally poorly conducting housing parts.

[0025] According to the invention, the new, substantially improved cooling device comprises a gas-tight cavity that forms a direct part of the electrical conductor, thus providing the shortest technically possible thermal conduction path and the highest technically possible thermal conductivity, since heat conduction takes place directly from the thermally highly conductive electrical conductor material into the phase-change material. In this way, the contact areas are locally equipped with a highly effective heat dissipation option.

[0026] Furthermore, it is advantageous according to the invention to increase the heat transfer from the electrical conductor into the phase change material by increasing the heat-transferring surface, for example by applying a rib structure.

[0027] Furthermore, it is advantageous according to the invention to increase the heat conduction within the volumetric installation space of the latent heat storage device by incorporating highly thermally conductive elements or structures, such as a highly porous metal foam matrix, or metal wool, or microparticles, etc., since this allows the volumetric progression of the phase transformation to be converted from an approximately two-dimensional dependence into a three-dimensional dependence.

[0028] A further advantage arises when the phase transition temperature of the phase transition material is selected in relation to the maximum permissible contact temperature, as well as in relation to a temperature sensor attached to the electrical conductor. The phase transition temperature is selected low enough to ensure that the temperature remains safely below the maximum permissible contact temperature as long as the phase transition material is not yet completely transformed. This physical effect is based on the 'quasi-isothermy' in the thermal system, since the melting temperature marks a constant temperature of the absorbing heat sink.If in such a case the temperature sensor for monitoring the contact temperature is thermally coupled to the heat sink, i.e. the phase change material, the moment of thermal saturation, i.e. the completely completed phase transformation during heat absorption, can be determined, since from this point on the measurable temperature at the sensor increases according to the thermal transfer function of the arrangement.

[0029] With such a unique temperature signal, a logical charging control function can be defined and functionally implemented, which marks a saturation of the phase change material heat sink in a time-flexible manner and, through a corresponding function signal, requests a reduction or limitation of the permissible charging current in such a way that a further temperature increase of the electrical contact geometry only occurs up to a predefined permissible maximum value, thus ensuring safe compliance with the maximum permissible contact temperature specified according to the technical device specification.

[0030] In a further preferred embodiment of this charging current limitation function controlled by the temperature sensor, it is assumed that, for technical and functional safety reasons, the charging system is temporarily mechanically and securely locked at the contact interface during the charging process. In a concrete example, this means that in an electrically powered vehicle, the charging gun, which is supplied with charging current from the external charging station, is securely connected in electrical contact by plugging it into the charging socket permanently installed in the vehicle, and the charging socket is locked by a locking unit, e.g., an electrically operated actuator, until a safety function in a control device enables unlocking, which is only permitted in a safe state. In the specific case, when the charging line has been de-energized and de-energized.

[0031] According to the invention, it is now proposed to integrate a new additional function into such a locking system, which also makes a temporary locking dependent on the contact temperature. From a functional perspective, this prevents the plug connection from being mechanically disconnected if areas of the electrical contact have temporarily exceeded the maximum temperature permitted according to the device specification. A temporary, temperature-dependent forced locking of the plug contact temporarily converts it into a "quasi-permanent" plug connection for the duration of the forced locking. This temporarily disregards the validity or applicability of the device specification for charging system plug connections, since the locking function does not allow for disconnection.The aim of this function is therefore to temporarily prevent the unlocking and separation of the charging system plug connection until the thermal boundary conditions of the plug connection, which is temporarily hermetically sealed by the locking mechanism, have returned to the range of validity of the device specification for such charging system plug connections through heat dissipation and cooling.

[0032] As a result of this functional safety measure, which is controlled based on the temperature sensor, the contact temperature of the electrical plug contact that occurs during the charging process can temporarily exceed the maximum contact temperature permitted by the standard without violating the requirements and definitions of the standard.

[0033] Below is an embodiment of the invention with reference to the attached Fig. 1 described.

[0034] In the Fig. 1 shows a charging system of an electrically powered vehicle 1 during a charging process. The charging system is shown in the Fig. 1 is shown schematically to the extent necessary for understanding the invention. Accordingly, the vehicle 1 is electrically connected via its charging socket 3 to a charging gun 5, which is connected to a power supply 9 as part of a charging infrastructure 7. The vehicle-mounted charging socket 3 has a number of pins or contact pins, of which Fig. 1 only one contact pin 10 is indicated. Accordingly, the charging gun 5 has a corresponding number of contact sockets, of which Fig. 1 also only shows a contact socket 11, which is in plug contact with the contact pin 10.

[0035] A core of the invention is that the contact pin 10 is divided into a cylindrical, small-cross-sectional contact pin base body 13 and a large-cross-sectional contact pin heat sink 15, both of which are made of the same material and / or are integral components of the contact pin 10. During the charging process, a charging current I flows through the contact area 8 between the contact pin 10 and the contact socket 11, so that the contact area 8 is heated by the influence of the ohmic contact resistance. This means that the main source of heat loss is the contact area 8 of the plug-in contact. From here, the heat is dissipated (by partial heating) proportionally into the contact pin base body 13 and the contact socket 11, which thereby experience a progressive temperature increase over time. The heat loss dissipated into the contact pin base body 13 is dissipated by means of the contact pin heat sink 15.

[0036] As from the Fig. 1, the cylindrical contact pin base body 13 is essentially made of a solid material, which is connected to a power line 17 on its connection side axially opposite the plug-in side. The connection is made according to the Fig. 1 by way of example by means of a screw connection, in which a screw bolt 19 is guided in the axial direction through a feed-through opening of the power line 17 and is in threaded engagement with an internally threaded hole 21 of the contact pin base body 13, so that the power line 17 is clamped between a bolt head of the screw bolt 19 and an opening edge region of the internally threaded hole 21 of the contact pin base body 13. The power line 17 is in the Fig. 1 starting from the contact pin 10 via a vehicle-side charger 18 to a traction battery 20 of the vehicle 1.

[0037] The cylindrical contact pin base body 15 is in the Fig. 1 is surrounded on its connection side by an annular space 23 of the contact pin heat sink 15, wherein the contact pin base body 15 projects beyond the contact pin heat sink 15 with an axial oversize to the plug-in side of the cylindrical contact pin base body 13. The annular space 23 is in the Fig. 1 is formed in the radial direction between the radially inner, small-cross-section contact pin base body 13 and a radially outer peripheral wall 25 of the contact pin heat sink 15. Furthermore, the annular space 23 is delimited on both sides by an end wall 27, 29, viewed in the axial direction.

[0038] In the Fig. 1, the annular space 23 is filled with a thermally active phase-change material 31, which acts as a cooling medium. The phase-change material 31 is designed to melt above a defined operating temperature while absorbing thermal energy. For example, its melting temperature can be in a range between 60°C and 70°C.

[0039] During the charging process, an actual temperature ϑ ist of the phase change material 31 is detected by a temperature sensor 33. This is in the Fig. 1 is positioned on the outside of the end wall 27 of the contact pin heat sink 15. The temperature sensor 33 is integrated into the arrangement in such a way that it is thermally connected in series with the phase change material 31, with the phase change material 31 being thermally connected between the heat-generating contact geometry and the temperature sensor 33. The temperature sensor 33 is thus thermally integrated into the system in such a way that its applicable temperature transfer function is fully defined and allows direct conclusions to be drawn about the actual contact temperature.

[0040] The temperature sensor 33 is in signal connection with an electronic evaluation unit 35, which measures the temporal course of the actual temperature ϑ istof the cooling medium 31. For example, if a continuity jump with a subsequent temperature increase occurs, the evaluation unit 35 can detect a complete and total melting of the phase change material 31. The phase change material 31 forms a latent heat accumulator that absorbs and stores the waste heat directly at the location of the heat generation and therefore prevents a further temperature increase in the contact area 8 between the contact pin base body 13 and the contact socket 11 until the phase change material 31 has completely melted.

[0041] The phase-change material 31 absorbs the heat loss from the contact geometry until it is exhausted. Until this point, the temperature and temperature gradient are maintained at a quasi-constant level. For example, a paraffin with a phase-change temperature of 64°C can be used as the phase-change material 31. This essentially limits the temperature in the phase-change material 31 and its surroundings to or below this value in the contact pin 10, as long as the phase-change material 31 is melted.

[0042] From the point of exhaustion, i.e. the complete melting of the phase change material 31, with further introduction of waste heat into the contact area 8, the temperature of the system increases proportionally to time and heat output according to a time-dependent temperature field.

[0043] Based on the actual temperature ϑ detected by the temperature sensor 33 istcan be reached at a contact temperature ϑ K in the contact area 8 between the contact pin 10 and the contact socket 11, taking into account a temperature gradient between the contact temperature ϑ K and the actual temperature ϑ ist due to heat transfer. In the evaluation unit 35, the actual temperature ϑ ist - taking into account the above-mentioned temperature gradient - with different temperature thresholds ϑ1, ϑ2, ϑ3. On the basis of this comparison, the evaluation unit 35 generates, if necessary, a charge limiting signal B1, B2, B3, with which the vehicle-side charger 18 can be controlled in order to limit the charging current I. According to the invention, depending on the actual temperature ϑ detected by the temperature sensor 33 ist a charging current limitation is carried out.

[0044] Of the temperature thresholds, a first temperature threshold ϑ1 is below a maximum value of the contact temperature ϑ K As soon as the actual temperature ϑ ist exceeds this first temperature threshold ϑ1, the evaluation unit 35 generates the charging current limiting signal B1, whereby the charger 18 carries out a first charging current limitation.

[0045] The second temperature threshold ϑ2 corresponds to the maximum permissible value of the contact temperature ϑ K . If the second temperature threshold ϑ2 is exceeded, the evaluation unit 35 generates a second charging current limiting signal B2, whereby the charger 18 implements a further charging current limit.

[0046] In the evaluation unit 35, a third temperature threshold ϑ3 is additionally stored, which is above the maximum value of the contact temperature ϑ Kand corresponds to a predefined maximum excess temperature. If the actual temperature ϑ ist is between the second temperature threshold ϑ2 and the third temperature threshold ϑ3, the charger 18 still allows a temporary or short-term energy transfer with further charging current limitation.

[0047] For example, exceeding the first temperature threshold ϑ1 (for example, 75°C) at the temperature sensor 33 corresponds to exceeding a first limit temperature in the electrical plug contact of, for example, 85°C.

[0048] Based on the first temperature threshold ϑ1, a charging current limitation function can be activated. This reduces the ohmic self-heating of the electrical plug contact by proportionally reducing the transmitted charging current I, since the power loss in the electrical plug contact is a function of the contact resistance and the square of the current flow I. This allows for thermally safe compensation for stochastic variations in the contact resistance. Furthermore, temperature-controlled, enhanced safety and control functions can be implemented, enabling control of the charging function as described below.

[0049] As already mentioned above, the device according to the invention has, as an additional function, a second temperature threshold ϑ2 and a third temperature threshold ϑ3, which are above the first temperature threshold ϑ1, wherein the second temperature threshold ϑ2 exactly represents the maximum contact temperature in the plug-in contact valid according to the device specification (i.e., for example, 90°C in the plug-in contact) and corresponds, for example, to 80°C at the temperature sensor 33. Furthermore, the third temperature threshold ϑ3 corresponds to a predefined maximum exceedance temperature in the electrical plug-in contact. For example, this maximum permissible short-term exceedance temperature at the plug-in contact can be defined as 100°C, which then corresponds, for example, to an actual temperature ϑ measured at the temperature sensor 33. istof 90°C. In this way, the charging process can be continued with variably adjustable charging power (charging current I) until the predefined maximum contact temperature is reached, temporarily exceeding the specified contact temperature and maintaining the specified contact temperature until the end of charging and unlocking process.

[0050] According to the Fig. 1, the charging system also has a locking unit 37, by means of which the plug contact between the contact pin 10 and the contact socket 11 can be locked. According to the invention, the locking can be dependent on the actual temperature ϑ detected by the temperature sensor 33 ist activated or released. For this purpose, the evaluation unit 35 generates an actual temperature ϑ ist, which is greater than the second temperature threshold ϑ2, a locking signal V, with which the locking unit 37 can be controlled in order to activate the locking between contact pin 10 and contact socket 11, namely until the actual temperature ϑ ist falls below the second temperature threshold ϑ2 again.

[0051] The actual temperature ϑ ist The defined locking function of the plug contact therefore prevents unlocking until the plug contact has cooled back down to the permissible limit temperature according to the device specifications (i.e., until the temperature falls below the second temperature threshold ϑ2 again during the cooling phase). The unlocking can then be released and the charging plug (i.e., the charging gun 5) removed, while fully adhering to the maximum temperature specified for the plug contact.

[0052] An evaluation of the charging time elapsed since the start of charging can also be functionally used to provide an estimate of the actual power loss generated, and thus of the existing contact resistance, for diagnostic purposes. This is done by measuring the point in time at which the temperature threshold is exceeded, which marks the complete conversion or melting of the latent heat storage medium. The amount of thermal energy that can be converted in the latent heat storage medium through phase transformation is predetermined by the design and is therefore known. If this amount of energy is then related to the charging time interval that has elapsed until melting, an average thermal power loss can be derived. This can be related to a calibrated limit value, which corresponds to a wear-dependent limit resistance. If this value is exceeded, the diagnostic function can then determine the wear status of the charging contact.

[0053] This can then be compared across multiple consecutive charging processes to identify trends and outliers. This allows a functional assignment to be made as to which part of the electrical contact is worn. In the case of an outlier, it can be statistically assumed that the wear issue is related to the specific charging nozzle of the charging station at which the charging process was carried out. In the case of a regular premature exceedance of the limit value, it can be assumed that the wear condition of the charging socket installed in the vehicle is increased. In both cases, a maintenance or repair request can be made via data transmission. List of reference symbols 1 vehicle 3 vehicle-side contact socket 5 loading pistol 7 Charging infrastructure 8 Contact area 9 Power supply 10 contact pin or pin 11 Contact socket 13 Contact pin base body 15 contact pin heat sink 17 Power line 18 Charger 19 screw bolts 20 traction battery 21 internal thread hole 23 Annular space 25 Perimeter wall 27, 29 front wall 31 Cooling medium 33 Temperature sensor 35 electronic evaluation unit 37 Locking unit 39 Rib structure B1, B2, B3 charging current limitation signals V Locking signal I Charging current ϑ ist Actual temperature ϑ K Contact temperature ϑ1, ϑ2, ϑ3 temperature thresholds

Claims

[1] Charging system of an electrically operated vehicle (1), with at least one vehicle-side contact pin (10) which can be brought into detachable plug contact with a contact socket (11) for energy transmission, which is assigned to a charging infrastructure (7), wherein during the energy transmission, heat loss is generated due to an electrical contact transmission resistance in the contact area (8) between the contact element (10) and the counter-contact element (11), characterized by that the device has a locking unit (37) which, depending on a contact temperature (ϑ K ) or a correlating actual temperature (ϑ ist) locks or releases the contact between the contact element (10) and the counter-contact element (11), that the contact pin (10) has a contact pin base body (13) and a contact pin heat sink (15), which are materially uniform and / or one-piece components of the contact pin (10) for increased heat dissipation, and that the contact pin heat sink (15) has a cavity (23) which is filled with a cooling medium (31). [2] Charging system according to claim 1, characterized by that at a contact temperature (ϑ K ) / Actual temperature (ϑ ist ) is greater than a temperature threshold (ϑ2), which corresponds in particular to a maximum value of the contact temperature (ϑ K ), the locking unit (37) locks the contact, and / or that at a contact temperature (ϑ K ) / Actual temperature (ϑ ist) less than or equal to the temperature threshold (ϑ2) the locking unit (37) releases the contact. [3] Charging system according to claim 1 or 2, characterized by that the locking unit (37) is assigned an evaluation unit (35) in which the current contact temperature (ϑ K ) or the corresponding actual temperature (ϑ ist ) is comparable to the temperature threshold (ϑ2), and that when the contact temperature / actual temperature is greater than the temperature threshold (ϑ2), the evaluation unit (35) generates a locking signal (V) with which the locking unit (37) can be controlled in order to activate the locking, in particular until the contact temperature / actual temperature (ϑ ist) falls below the temperature threshold (ϑ2), and / or that when the contact temperature / actual temperature is less than or equal to the temperature threshold (ϑ2), the evaluation unit (35) generates a release signal (F) with which the locking unit (37) can be controlled in order to release the locking. [4] Charging system according to one of the preceding claims, characterized by that the device has at least one temperature sensor (33) for detecting the actual temperature (ϑ ist ) which is in signal connection with an evaluation unit (35), and in particular based on the actual temperature (ϑ ist ) to the contact temperature (ϑ k ) in the contact area (8) between the contact element (10) and the counter-contact element (11) can be closed, in particular taking into account a temperature gradient between the contact area (8) and the temperature sensor (33). [5] Charging system according to one of the preceding claims, characterized by that the cooling medium (31) is designed to melt above a defined operating temperature by absorbing thermal energy, and that in particular the cooling medium (31) is a thermally active phase change material, such as paraffin, and that in particular the evaluation unit (35) detects melting of the cooling medium (31) in the presence of a continuity jump with subsequent temperature increase in the temporal actual temperature profile. [6] Charging system according to claim 5, characterized bythat the in particular cylindrical contact pin base body (13) extends in an axial direction through the cavity (23) of the contact pin heat sink (15), and that in particular the cavity (23) is an annular space surrounding the contact pin base body (13), and that in particular the annular space (23) is formed in the radial direction between the radially inner contact pin base body (13) and a radially outer circumferential wall (25) of the contact pin heat sink (15), and / or that in particular the contact pin base body (15) projects beyond the contact pin heat sink (15) with an axial oversize to the plug-in side of the cylindrical contact pin base body 13, and / or that in particular the annular space (23) is delimited on both sides in the axial direction by an end wall (27, 29), and that in particular each end wall (27, 29) has a passage through which the contact pin base body (13) extends. [7] Charging system according to claim 4, 5 or 6, characterized bythat the actual temperature (ϑ ist ) of the cooling medium (31) can be detected, and in particular as a function of the actual temperature (ϑ ist ) a charging current limitation takes place, and that in particular in the evaluation unit (35) the actual temperature (ϑ ist ) - in particular taking into account the temperature gradient - is compared with at least one temperature threshold (ϑ1) stored in the evaluation unit (35), and that the evaluation unit (35) generates, on the basis of this comparison, a charging limiting signal (B1, B2, B3) with which a vehicle-side charging device (18) can be controlled in order to limit the charging current (I) flowing through the device. [8] Charging system according to claim 7, characterized by that a first temperature threshold (ϑ1) is below a maximum value of the contact temperature (ϑ K), that when the first temperature threshold (ϑ1) is exceeded, the charger (18) carries out a first charging current limitation, that in particular a second temperature threshold (ϑ2) is provided which is above the first temperature threshold (ϑ1), which preferably corresponds to the maximum value of the contact temperature (ϑ K ), and that in particular when the second temperature threshold (ϑ2) is exceeded, the charger (18) interrupts the charging current or further limits the charging current, and that in particular in the evaluation unit (35) a third temperature threshold (ϑ3) is stored, which is above the maximum value of the contact temperature (ϑ K ) and corresponds to a predefined maximum excess temperature, and that in particular at an actual temperature (ϑ ist) between the second and third temperature threshold (ϑ2, ϑ3) the charger (18) still allows a temporary or short-term energy transfer with, if necessary, a further charging current limitation. [9] Method for operating a charging system of an electrically powered vehicle (1), with at least one vehicle-side contact pin (10) which can be brought into detachable plug-in contact with a contact socket (11) for energy transmission, which is assigned to a charging infrastructure (7), wherein during the energy transmission, heat loss is generated due to an electrical contact transmission resistance in the contact area (8) between the contact element (10) and the counter-contact element (11), characterized by that the device has a locking unit (37) which, depending on a contact temperature (ϑ K ) or a correlating actual temperature (ϑ ist) locks or releases the contact between the contact element (10) and the counter-contact element (11), that the contact pin (10) has a contact pin base body (13) and a contact pin heat sink (15), which are materially uniform and / or one-piece components of the contact pin (10) for increased heat dissipation, and that the contact pin heat sink (15) has a cavity (23) which is filled with a cooling medium (31).

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