An overhead electric charging system and truck terminal

Abstract

An electric charging system for an electric vehicle comprises a direct voltage power supply, direct voltage rails (109, 110) connected to the direct voltage power supply, and a supply sledge (118) moveable along the direct voltage rails The supply sledge comprises contact elements (111, 112) for forming galvanic contacts with the direct voltage rails, electric conductors (113) galvanically connected to the contact elements, and a charging plug (114) galvanically connected to the electric conductors and connectable to a charging socket of an electric vehicle. The electric conductors of the supply sledge comprise downwards-directed rails (119, 120) whose upper ends are galvanically connected to the contact elements and lower ends are galvanically connected to an end of a cable (121) whose other end is provided with the charging plug. Due to the downwards-directed rails, the cable can be shorter, which makes it possible to reduce power losses and improve cooling.

Description

[0001] AN OVERHEAD ELECTRIC CHARGING SYSTEM AND TRUCK TERMINAL

[0002] Field

[0003] The invention relates generally to charging of electric vehicles. More particularly, the invention relates to an electric charging system for charging an electric vehicle such as e.g. an electric truck, an electric van, or an electric car. Furthermore, the invention relates to a truck terminal for loading and unloading goods to and from electric trucks and for charging the electric trucks.

[0004] Background

[0005] A typical electric charging system for charging an electric vehicle comprises an alternating or direct voltage energy supply and an electric conductor arrangement for transferring electric energy from the energy supply to a charging plug connectable to a charging socket of the electric vehicle. Publication US20120013300A1 describes a charging system for reaching and charging electric vehicles parked in a pair of adjacent rows of side-by-side parking spaces. The charging system described in publication US20120013300A1 comprises a rail, a pair of trolleys, an electric vehicle charger, and apparatus for electrically connecting the electric vehicle charger to a power source without impinging upon movement of the pair of trolleys along the rail. The rail mounts overhead of, and traverses, the pair of adjacent rows of side-by-side parking spaces. The pair of trolleys are movably mounted along the rail and reach the electric vehicles parked in the pair of adjacent rows of the side-by-side parking spaces. The electric vehicle charger is mounted on, and moves with, the pair of trolleys to charge the electric vehicles parked in the pair of adjacent rows of the side-by-side parking spaces. The electric vehicle charger comprises a connection cable whose end is provided with a charging plug connectable to a charging socket of an electric vehicle.

[0006] An inherent challenge related to charging systems of the kind described in publication US20120013300A1 is that the above-mentioned connection cable can be rather long especially in cases where a charging system is designed for high vehicles such as electric trucks and thereby the distance from the ground to a rail supporting the electric vehicle charger must be quite long. When charging electric trucks, charging power can be on megawatt-level, which means that power losses in a connection cable can be of the order of 2-3 kilowatts per mater. Therefore, there is a need for charging systems where the above-described problem related to long connection cables can be avoided or at least reduced.

[0007] Summary

[0008] The following presents a simplified summary to provide a basic understanding of some embodiments of the invention. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments.

[0009] In this document, the word “geometric” when used as a prefix means a geometric concept that is not necessarily a part of any physical object. The geometric concept can be for example a geometric point, a straight or curved geometric line, a geometric plane, a non-planar geometric surface, a geometric space, or any other geometric entity that is zero, one, two, or three dimensional.

[0010] In accordance with the invention, there is provided a new electric charging system for charging an electric vehicle. In this document, the term “electric vehicle” covers not only all-electric vehicles but also pluggable hybrid vehicles which comprise both one or more electric motors and a combustion motor.

[0011] An electric charging system according to the invention comprises:

[0012] - a direct voltage power supply,

[0013] - direct voltage rails connected to the direct voltage power supply and thus having a direct voltage therebetween and being i) bars of rigid and electrically conductive material e.g. copper, ii) parallel with each other, and iii) a distance over ground, and - a supply sledge moveable along the direct voltage rails and comprising contact elements configured to form galvanic contacts with the direct voltage rails, electric conductors galvanically connected to the contact elements, and a charging plug galvanically connected to the electric conductors and connectable to a charging socket of the electric vehicle to supply electric energy from the direct voltage rails to the electric vehicle.

[0014] The above-mentioned electric conductors of the supply sledge comprise downwards-directed rails that are bars of rigid and electrically conductive material and parallel with each other such that upper ends of the downwards-directed rails are galvanically connected to the contact elements and lower ends of the downwards-directed rails are galvanically connected to a first end of a cable whose second end is provided with the charging plug.

[0015] Due to the downwards-directed rails, the above-mentioned cable can be significantly shorter than a distance from the direct voltage rails to a charging socket of an electric vehicle to be charged. It is straightforward to arrange cross-sectional areas of the downwards-directed rails to be greater than corresponding cross-sectional areas of electric conductors of the cable. Thus, power losses per meter can be significantly smaller in the downwards-directed rails than in the cable. This is significant especially when charging power is on megawatt-level.

[0016] In accordance with the invention, there is also provided a new truck terminal for loading and unloading goods to and from electric trucks and for charging the electric trucks.

[0017] A truck terminal according to the invention comprises a direct voltage power supply system and one or more loading docks each being suitable for receiving a back of an electric truck for loading and unloading goods through the back of the electric truck. Each of the one or more loading docks comprises an electric charging system according to the invention so that the direct voltage rails of the electric charging system are perpendicular to the loading dock and parallel with a longitudinal direction of the electric truck when the electric truck is at the loading dock, and the direct voltage power supply system of the truck terminal constitutes the direct voltage power supply of the electric charging system of each of the one or more loading docks.

[0018] Exemplifying and non-limiting embodiments are described in accompanied dependent claims.

[0019] Various exemplifying and non-limiting embodiments both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying and nonlimiting embodiments when read in conjunction with the accompanying drawings.

[0020] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of un-recited features.

[0021] The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated.

[0022] Furthermore, it is to be understood that the use of “a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.

[0023] Brief description of figures

[0024] Exemplifying and non-limiting embodiments and their advantages are explained in greater detail below in the sense of examples and with reference to the accompanying drawings, in which: figures 1 a and 1 b illustrate an electric charging system according to an exemplifying and non-limiting embodiment, figure 2 illustrates a detail of an electric charging system according to an exemplifying and non-limiting embodiment, figure 3 illustrates a detail of an electric charging system according to an exemplifying and non-limiting embodiment, figures 4a and 4b illustrate a truck terminal comprising electric charging systems according to an exemplifying and non-limiting embodiment, and figures 5a and 5b illustrate a truck terminal comprising electric charging systems according to an exemplifying and non-limiting embodiment.

[0025] Description of exemplifying and non-limiting embodiments

[0026] The specific examples provided in the description below should not be construed as limiting the scope and / or the applicability of the accompanied claims. Lists and groups of examples provided in the description are not exhaustive unless otherwise explicitly stated.

[0027] Figure 1 a shows a schematic side view of an electric charging system according to an exemplifying and non-limiting embodiment. The electric charging system comprises a direct voltage power supply 153 that may comprise for example an alternating current - direct current “AC-DC” converter connected to an AC power grid. The AC power grid is not shown in figure 1 a. The electric charging system comprises direct voltage rails which are parallel with each other, a distance over the ground, and connected to the direct voltage power supply 153 and thus have a direct voltage therebetween. The direct voltage rails are bars of rigid and electrically conductive material, e.g. copper. In figure 1 a, one of the direct voltage rails is denoted with a reference 109 and the longitudinal direction of the direct voltage rails is parallel with the y-axis of a coordinate system 199. The exemplifying electric charging system illustrated in figure 1 a comprises a support beam 116 parallel with the direct voltage rails. The direct voltage rails are mechanically attached to the support beam 116 with the aid of electric insulator elements. It is also possible that electric charging system according to an exemplifying and non-limiting embodiment does not comprise a support beam of the kind mentioned above but the electric charging system comprises girder bridges each of which extends over the direct voltage rails in the transverse direction of the direct voltage rails, and the direct voltage rails are suspended with electrically insulating suspension elements from the one or more girder bridges.

[0028] The electric charging system comprises a supply sledge 118 that is moveable along the direct voltage rails. Figure 1 b shows a schematic section view of the supply sledge 118. The section has been taken along a geometric line A-A shown in figure 1 a, and the geometric section plane is parallel with the xz-plane of the coordinate system 199. In figure 1 b, the cross-sections of the direct voltage rails are denoted with references 109 and 110, and the electric insulator elements mechanically supporting the direct voltage rails 109 and 110 with respect to the support beam 116 are denoted with a reference 117. The support beam 116 is between the direct voltage rails 109 and 110 so that each geometric line between these direct voltage rails intersects the support beam 116. The support beam 116 is advantageously connected to the ground potential as it is schematically shown in figure 1 a. Thus, there is no direct route for a short circuit arc between the direct voltage rails 109 and 110. In this exemplifying case, the support beam 116 is an I-beam as shown in figure 1 b. A middle part 150 of the I-beam is between the direct voltage rails 109 and 110, and side parts 151 of the I-beam cover the direct voltage rails when seen along a direction perpendicular to the side parts, i.e. when seen along the z-axis of the coordinate system 199. In this exemplifying case, the direct voltage rails 109 and 110 are horizontally parallel with each other but also different arrangements are possible. For example, one direct voltage rail can be vertically or obliquely above another direct voltage rail.

[0029] The supply sledge 118 comprises contact elements 111 and 112 configured to form galvanic contacts with the direct voltage rails 109 and 110, respectively. In this exemplifying case, the contact elements 111 and 112 are pressed by springs 122 and 123 against the direct voltage rails 109 and 110 to provide contact forces between the contact elements 111 and 112 and the direct voltage rails 109 and 110. The supply sledge 118 comprises electric conductors 113 galvanically connected to the contact elements 111 and 112 and a charging plug 114 galvanically connected to the electric conductors and connectable to a charging socket 115 of an electric vehicle 106 to supply electric energy from the direct voltage rails 109 and 110 to the electric vehicle 106. The electric conductors 113 comprise downwards-directed rails 119 and 120 which are bars of rigid and electrically conductive material, e.g. copper, and parallel with each other. The upper ends of the downwards-directed rails 119 and 120 are galvanically connected to the contact elements 111 and 112 and the lower ends of the downwards-directed rails 119 and 120 are galvanically connected to a first end of a flexible cable 121 whose second end is provided with the charging plug 114. Due to the downwards-directed rails 119 and 120, the flexible cable 121 can be significantly shorter than a distance from the direct voltage rails 109 and 110 to a charging socket of an electric vehicle to be charged. It is straightforward to arrange cross-sectional areas of the downwards-directed rails 119 and 120 to be greater than corresponding cross-sectional areas of electric conductors of the flexible cable 121 . Thus, power losses per meter can be significantly smaller in the downwards-directed rails 119 and 120 than in the flexible cable 121. This is significant especially when charging power is on megawatt-level.

[0030] Charging power of an electric charging system according to an exemplifying and non-limiting embodiment can be for example at least 200 kW, or at least 400 kW, or at least 600 kW, or at least 800 kW, or at least 1 MW, or at least 1 .2 MW. Dimensions of the cross-section of each of the downwards-directed rails 119 and 120 can be e.g. 10 mm x 100 mm or 10 mm x 80 mm. In an exemplifying case where the cross- sectional dimensions are 10 mm x 100 mm and the material of the direct voltage rail is copper having resistivity 1.68 xW8Qm, the resistance per meter of the direct voltage rail is 1.68 xW5Q / m. If the current is e.g. 1500 A, the power loss per meter is 37.8 W / m. In stagnant air, the cooling efficiency is about 10W / °C / m2Thus, the temperature rise is about 3.78 °Cm2 / (2 x o.1 m x 1 m + 2 x 0.01 m x 1 m) = 172°C. In a typical flexible cable, the power loss per meter can be from 2 to 3 kW which is significantly higher than the above-mentioned 37.8 W / m.

[0031] The exemplifying supply sledge 118 illustrated in figure 1 b comprises a cooling duct 128 for circulating cooling fluid to cool the electric conductors 113 configured to transfer the electric energy from the supply sledge 118 to the charging plug 114. The cooling fluid can be e.g. transformer oil. In cases where electric conductors having voltage are insulated from the cooling fluid and thus the cooling fluid does not need to be electrically insulating, the cooling fluid can be e.g. water-glycol mixture. In the exemplifying case shown in figure 1 b, the supply sledge 118 comprises a circulation pump and a heat-exchanger 126 configured to transfer heat from the cooling fluid to the ambient air. The circulation path of the cooling fluid is depicted with a dashed line 127. It is also possible that the supply sledge 118 is connected with a flexible hose to an external system for circulating cooling fluid. In the exemplifying case illustrated in figure 1 b, the direct voltage rails 109 and 110 have longitudinal cooling channels 124 and 125. The direct voltage rails 109 and 110 can be connected with electrically insulating pipes to a cooling system for circulating cooling fluid through the direct voltage rails 109 and 110.

[0032] An electric charging system according to an exemplifying and non-limiting embodiment comprises a sensor system configured to produce sensor data indicative of a position of the front of an electric vehicle when the electric vehicle is on a charging area of the electric charging system. The sensor system may comprise for example a laser sensor, a radio sensor, an ultrasonic sensor, a machine vision system, and / or one or more inductor loops in / on a ground of the charging area occupied by an electric vehicle to be charged. In figure 1 a, a device that can be e.g. a laser sensor, a radio sensor, an ultrasonic sensor, or a camera of a machine vision system is denoted with a reference 132. An inductor loop is denoted with a reference 133.

[0033] The exemplifying supply sledge 118 illustrated in figure 1 b comprises a servomotor 130 configured to drive toothed wheels 131 which mesh with toothed bars on an upper surface of the support beam 116 to move the supply sledge 118 along the direct voltage rails 109 and 110. Instead of the toothed wheels 131 , it is also possible to use drive wheels coated with rubber or other suitable material which provides sufficient friction with respect to the surface of the support beam 116. It is also possible that a servomotor for moving the supply sledge is located at an end of the support beam 116 and the supply sledge 118 is moved by a wire rope or chain arrangement driven by the servomotor. In the exemplifying case illustrated in figure 1 b, the toothed wheels 131 support the supply sledge 118 vertically with respect to the support beam 116. The supply sledge 118 is horizontally supported by guide wheels 134 with respect to the support beam 116. The exemplifying supply sledge 118 illustrated in figure 1 b comprises a counterweight 152 for compensating for unbalance caused by the weight of the electric conductors 113 so that the electric conductors 113 and the counterweight 152 are on opposite sides with respect to the direct voltage rails 109 and 110, and with respect to the support beam 116. In this exemplifying case, the heat-exchanger 126 and the circulation pump constitute at least a part of the counterweight 152. Furthermore, there can be guide wheels at the lower part of the support beam 116 as shown in figure 1 b to prevent tilting of the supply sledge 118. In the exemplifying case illustrated in figure 1 b, the supply sledge 118 comprises a controller 161 that is configured to control the servomotor 130 to move the supply sledge 118 to a position determined by the sensor data indicative of a position of the front of an electric vehicle. The position can be e.g. 1 -3 meters backwards from the position of the front of the electric vehicle.

[0034] The electric charging system may comprise for example a control system that is configured to carry out a loading-handshake after connecting the charging plug 114 to a charging socket of an electric vehicle. To carry out the loading-handshake and possible other phases of a charging protocol, there is typically a need for information transfer from the charging plug to control means of the direct voltage power supply. The exemplifying electric charging system illustrated in figure 1 a comprises a flexible data transfer cable 129 between the direct voltage power supply 153 and the supply sledge 118 and another data transfer cable between the supply sledge 118 and the charging plug 114. The data transfer cable between the supply sledge 118 and the charging plug 114 is depicted schematically with a dash-and-dot line in figure 1 b. The flexible data transfer cable 129 is folded in response to a movement of the supply sledge 118 towards the direct voltage power supply 153 and is straightened in response to a movement of the supply sledge 118 away from the direct voltage power supply 153. It is also possible that the information transfer is implemented with e.g. a short-range radio link.

[0035] In addition to the above-mentioned information transfer, there can be a need for electric power within the supply sledge 118 because the supply sledge 118 may comprise one or more devices needing electricity, such as the circulation pump for circulating cooling fluid, the servomotor 130 for moving the supply sledge, and / or one or more sensors. The above-mentioned flexible data transfer cable 129 can be a combined data transfer and power cable that comprises electric conductors for e.g. 230 V AC. It is also possible that the supply sledge 118 comprises a DC-DC and / or a DC-AC converter configured to convert the DC voltage of the direct voltage rails 109 and 110 into one or more voltages suitable for one or more devices which need electricity within the supply sledge 118. In this exemplifying case, the supply sledge 118 may further comprise an energy storage e.g. a battery for supplying energy in situations in which energy cannot be taken from the direct voltage rails 109 and 110. Figure 2 shows a schematic section view of a part of a supply sledge 218. The geometric section plane is parallel with the xz-plane of a coordinate system 299 and perpendicular to the longitudinal direction of direct voltage rails 209 and 210 and a support beam 216. In the exemplifying case illustrated in figure 2, the supply sledge 218 comprises a force-control system configured to change, responsive to a control signal 238, contact forces between contact elements 211 and 212 and the direct voltage rails 209 and 210. The force-control system comprises electromagnets 235 and 236 configured to press the contact elements 211 and 212 against the direct voltage rails 209 and 210 in response to electric currents supplied to the electromagnets. The electromagnets 235 and 236 can be solenoids which draw rods 237 upwards when electric currents are supplied to the electromagnets 235 and 236. In this exemplifying case, the electromagnets 235 and 236 are configured act against the gravity force when pressing the contact elements 211 and 212 against the direct voltage rails 209 and 210. Thus, the gravity force detaches the contact elements 211 and 212 from the direct voltage rails 209 and 210 in absence of electric currents in the electromagnets 235 and 236, for example in a fault situation. Furthermore, the force-control system can be provided with springs 238 and 239 configured to detach the contact elements 211 and 212 from the direct voltage rails 209 and 210 in absence of electric currents in the electromagnets 235 and 236.

[0036] The electric charging system that comprises the supply sledge 218 may comprise for example a control system 240 that is configured to carry out a loading-handshake after connecting a charging plug to a charging socket of an electric vehicle and to form the above-mentioned control signal 238 so that the contact forces between the contact elements 211 and 212 and the direct voltage rails 209 and 210 are increased in response to the loading-handshake and decreased after charging the electric vehicle. The loading-handshake can be according to for example any suitable known charging protocol. It is however also possible that the control signal 238 is generated manually via a user interface in conjunction when connecting the charging plug to a charging socket of an electric vehicle. In general, the control signal 238 for making contacts between the contact elements and the direct voltage rails can be generated in many ways. In addition to the above-mentioned examples, the contacts can be made for example in response to a situation in which the supply sledge is, according to sensor data, at a predetermined position with respect to an electric vehicle, in response to a situation in which the supply sledge is, according to sensor data, within a predetermined distance from a charging socket of an electric vehicle, in response to a situation in which the supply sledge has been at a standstill for a predetermined time, and / or in response to a situation in which the charging plug has been removed from its holder. It is to be noted that the embodiment illustrated in figure 2 is not limited to any specific ways to generate the control signal 238 to control the contact forces between the contact elements 211 and 212 and the direct voltage rails 209 and 210.

[0037] Figure 3 shows a schematic section view of a part of a supply sledge 318. The geometric section plane is parallel with the xz-plane of a coordinate system 399 and perpendicular to the longitudinal direction of direct voltage rails 309 and 310 and a support beam 316. In the exemplifying case illustrated in figure 3, the supply sledge 318 comprises a force-control system configured to change, responsive to a control signal 338, contact forces between contact elements 311 and 312 and the direct voltage rails 309 and 310. The force-control system comprises a support control system 341 that is configured to control a mechanical support of the supply sledge 318 with respect to the support beam 316 by changing a distance D shown in figure 3. The support control system 341 may comprise e.g. one or more threaded rods which is / are rotated with a servomotor, or which are non-rotating and one or more threaded elements surrounding the one or more threaded rods is / are rotated with a servomotor. In is also possible that the support control system 341 comprises a worm gear meshing with a toothed bar. When the distance D is increased, the supply sledge 318 moves upwards, i.e. in the positive z-direction of the coordinate system 399, and therefore the contact elements 311 and 312 get off the direct voltage rails 309 and 310. Correspondingly, when the distance D is decreased the weight of the supply sledge 118 gets more and more carried by the contact forces between the contact elements 311 and 312 and the direct voltage rails 309 and 310. The electric charging system that comprises the supply sledge 318 may comprise a control system 340 that is configured to carry out a loading-handshake after connecting a charging plug to a charging socket of an electric vehicle and to form the above- mentioned control signal 338 so that the contact forces between the contact elements 311 and 312 and the direct voltage rails 309 and 310 are increased in response to the loading-handshake and decreased after charging the electric vehicle. It is however also possible that the control signal 338 is generated manually via a user interface in conjunction when connecting the charging plug to a charging socket of an electric vehicle. It is to be noted that the embodiment illustrated in figure 3 is not limited to any specific ways to generate the control signal 338 to control the contact forces between the contact elements 311 and 312 and the direct voltage rails 309 and 310.

[0038] Figure 4a shows a schematic top view of a truck terminal according to an exemplifying and non-limiting embodiment for electric trucks. The truck terminal comprises a direct voltage power supply system 401 and loading docks 402, 403, 404, and 405. Each of the loading docks 402-405 is suitable for receiving a back of an electric truck for loading and unloading goods through the back of the electric truck. In the exemplifying situation shown in figure 4a, an electric truck 406 is at the loading dock 402, an electric truck 407 is at the loading dock 404, and the loading docks 403 and 405 are empty. In figure 4a, the longitudinal direction of the electric trucks 406 and 407 is parallel with the y-axis of a coordinate system 499.

[0039] Each of the loading docks 402-405 comprises an electric charging system according to an exemplifying and non-limiting embodiment so that the direct voltage rails of the electric charging system are perpendicular to the loading dock and parallel with a longitudinal direction of an electric truck when the electric truck is at the loading dock. In figure 4a, the supply sledge of the electric charging system of the loading dock 402 is denoted with a reference 418. In this exemplifying case, each of the loading docks 402-405 comprises a support beam perpendicular to the loading dock and parallel with the longitudinal direction of an electric truck when the electric truck is at the loading dock. The direct voltage rails of the electric charging system of the loading dock are mechanically attached to the support beam with the aid of electric insulator elements. In figure 4a, the support beam of the loading dock 402 is denoted with a reference 416.

[0040] The direct voltage power supply system 401 constitutes the direct voltage power supplies of the electric charging systems of the loading docks 402-405. In figure 4a, the direct voltage power supply of the loading dock 402 is denoted with a reference 453. In the exemplifying truck terminal illustrated in figure 4a, the direct voltage power supply system 401 comprises alternating current - direct current “AC-DC” converters so that each loading dock has one of the AC-DC converters. Each of these AC-DC converters can be connected separately to an AC power grid or there can be e.g. a common transformer connected to the AC power grid and arranged to supply energy to the AC-DC converters. The AC power grid is not shown in figure 4a. It is also possible that a direct voltage power supply system of a truck terminal according to an exemplifying and non-limiting embodiment comprises a common AC-DC converter and each loading dock has a DC-DC converter. The DC-DC converters can be in the vicinity of the ends of the direct voltage rails near to a building 408 of the truck terminal, and the DC-DC converters can be connected to the direct voltage rails with rigid bars or with flexible cables. Depending on power levels it may be also possible that the DC-DC converters are in the supply sledges. Thus, the invention is not limited to any specific architecture or architectures of the direct voltage power supply system.

[0041] Figure 4b shows a schematic side view of the loading dock 402 of the truck terminal illustrated in figure 4a. The viewing direction related to figure 4b is illustrated by the coordinate system 499. In this exemplifying case, there are vertical beams 460 configured to sustain the support beam 416. The vertical beams 460 are advantageously as near as possible to the building 408 of the truck terminal to minimize the harm they cause to truck handling. A truck terminal according to an exemplifying and non-limiting embodiment comprises a girder bridge that extends over the direct voltage rails of many loading docks in the transverse direction of the direct voltage rails, and the support beams are suspended from the girder bridge. It is also possible that the direct voltage rails are suspended with electrically insulating suspension elements from the girder bridge, in which case the whole weight of each supply sledge can be carried by the respective the direct voltage rails, i.e. there is no support beam. The girder bridge and its possible vertical support pillars may have e.g. a lattice structure to minimize weight while maximizing stiffness.

[0042] In the exemplifying truck terminal illustrated in figure 4a, the direct voltage rails of each loading dock are beside an area occupied by an electric truck when the electric truck is at the loading dock when the truck terminal is seen from above as shown in figure 4a. In figure 4b, one of the direct voltage rails of the electric charging system of the loading dock 402 is denoted with a reference 409. Figure 5a shows a top view of a truck terminal according to another exemplifying and non-limiting embodiment where at least parts of direct voltage rails of each of loading docks 502, 503, 504, and 505 are above an area occupied by an electric truck when the electric truck is at the loading dock. In the exemplifying situation shown in figure 5a, an electric truck 506 is at the loading dock 502, an electric truck 507 is at the loading dock 504, and the loading docks 503 and 505 are empty. Figure 5b shows a schematic side view of the loading dock 502 of the truck terminal illustrated in figure 5a. The viewing direction related to figure 5b is illustrated by a coordinate system 599. In figure 5b, one of the direct voltage rails of the electric charging system of the loading dock 502 is denoted with a reference 509, a support beam of the loading dock 502 is denoted with a reference 516, and a supply sledge of the electric charging system of the loading dock 502 is denoted with a reference 518.

[0043] In the exemplifying truck terminal illustrated in figure 4a, a cooling system of the direct voltage power supply system 401 comprises an adjustable heat transfer channeling 444 switchable to a first position in which the adjustable heat transfer channeling is configured to give off heat inside the building 408 of the truck terminal and to a second position in which the adjustable heat transfer channeling is configured to give off heat outside the building 408 of the truck terminal. The first position is suitable for cases, e.g. during a winter, where power losses of the direct voltage power supply system 401 are wanted to be used for warming up the building 408 of the truck terminal, whereas the second position is suitable for cases, e.g. during a summer, where there is a desire to avoid warming up the building 408. The power losses of the direct voltage power supply system 401 can be tens of kilowatts because charging powers related to the loading docks 402-405 can be on megawatt-level.

[0044] The above-mentioned cooling system can be for example a liquid cooling system in which case the adjustable heat transfer channeling 444 is a liquid circulation channeling, a heatsink 442 inside the building 408 can be a heat exchanger as well as a heatsink 443 outside the building 408 can be a heat exchanger. It is also possible that the cooling system is an air cooling system in which case the adjustable heat transfer channeling 444 can be a flow-through channeling, the heatsink 442 inside the building 408 can be simply an open end of a channel for blowing warm cooling air into the interior of the building 408, and correspondingly the heatsink 443 outside the building 408 can be simply an open end of a channel for blowing warm cooling air to the ambient air outside the building 408. In the exemplifying truck terminal illustrated in figure 4a, the AC-DC converters of the direct voltage power supply system 401 are located inside the building 408. This is a suitable arrangement for a cold atmosphere because a part of power losses which is not carried by cooling air or cooling liquid within the channeling 444, but which is emitted to surroundings through e.g. casings of the AC-DC converters warms up the building 408.

[0045] In the exemplifying truck terminal illustrated in figure 5a, a direct voltage power supply system 501 comprises AC-DC converters each of which comprises an adjustable heat transfer channeling switchable to a first position in which the adjustable heat transfer channeling is configured to blow warm cooling air into the interior of a building 508 of the truck terminal and to a second position in which the adjustable heat transfer channeling is configured to blow the warm cooling air to the ambient air outside the building 508. In the exemplifying truck terminal illustrated in figure 5a, the AC-DC converters of the direct voltage power supply system 501 are located outside the building 508. This is a suitable arrangement for a hot atmosphere because a part of power losses which is not carried by the above- mentioned cooling air, but which is emitted to surroundings through e.g. casings of the AC-DC converters does not warm up the building 508.

[0046] In the exemplifying truck terminal illustrated in figure 5a, the direct voltage power supply system 501 comprises a switch module 545 comprising controllable switches capable of connecting each of the AC-DC converters to supply electric energy to the direct voltage rails of desired one or more of the loading docks 502-505. Therefore, desired one or more of the AC-DC converters can be connected to supply electric energy to desired one or more of the loading docks 502-505. The AC-DC converters shown in figure 5a can be separate AC-DC converters or they can be converter modules of a modular AC-DC converter system such that each of the modules has a module-specific direct voltage outlet. It is also possible that the direct voltage power supply system 501 comprises one or more AC-DC converters configured to supply one or more DC intermediate circuits and DC-DC converters supplied by the one or more DC intermediate circuits and having direct voltage outlets each of which can be connected, with the aid of the switch module, to supply electric energy to the direct voltage rails of desired one or more of the loading docks 502-505. Thus, different AC-DC conversion systems are possible for supplying electric energy from an AC power 550 grid to direct voltage outlets of the kind mentioned above. Furthermore, the AC-DC conversion system can be configured to be bi-directional so that electric energy can be transferred from a battery of an electric truck to the AC power grid.

[0047] In the exemplifying case illustrated in figure 5a, the switch module 545 enables the direct voltage outlets of the AC-DC converters to be connected in parallel with each other. It also possible that a switch module enables series connections between the direct voltage outlets of the AC-DC converters and / or mixed parallel-series connections between the direct voltage outlets of the AC-DC converters, e.g. a parallel connection of series connected sub-groups of the AC-DC converters and / or a series connection of parallel connected sub-groups of the AC-DC converters.

[0048] The specific examples provided in the description given above should not be construed as limiting the scope and / or the applicability of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.

Claims

What is claimed is:

1. An electric charging system for charging an electric vehicle, the electric charging system comprising:- a direct voltage power supply (153, 453, 553),- direct voltage rails (109, 110, 209, 210, 309, 310) connected to the direct voltage power supply and thus having a direct voltage therebetween and being i) bars of rigid and electrically conductive material, ii) parallel with each other, and iii) a distance over ground, and- a supply sledge (118, 218, 318, 418, 518) moveable along the direct voltage rails and comprising contact elements (111 , 112, 211 , 212, 311 , 312) configured to form galvanic contacts with the direct voltage rails, electric conductors (113) galvanically connected to the contact elements, and a charging plug (114) galvanically connected to the electric conductors and connectable to a charging socket of the electric vehicle to supply electric energy from the direct voltage rails to the electric vehicle, characterized in that the electric conductors (113) of the supply sledge (118, 218, 318, 418, 518) comprise downwards-directed rails (119, 120) being bars of rigid and electrically conductive material and parallel with each other such that upper ends of the downwards-directed rails are galvanically connected to the contact elements (111 , 112, 211 , 212, 311 , 312) and lower ends of the downwards-directed rails are galvanically connected to a first end of a cable (121 ) whose second end is provided with the charging plug.

2. An electric charging system according to claim 1 , wherein the electric charging system comprises a support beam (116, 316, 416, 516) parallel with the direct voltage rails, and electric insulator elements (117) configured to mechanically support the direct voltage rails with respect to the support beam.

3. An electric charging system according to claim 2, wherein the support beam is galvanically connected to ground potential.

4. An electric charging system according to claim 2 or 3, wherein the support beam (116) is between the direct voltage rails (109, 110) so that each geometric line between the direct voltage rails intersects the support beam.

5. An electric charging system according to claim 4, wherein the support beam (116) is an I-beam, a middle part (150) of the I-beam is between the direct voltage rails, and side parts (151 ) of the I-beam cover the direct voltage rails when seen along a direction (z) perpendicular to the side parts (151 ).

6. An electric charging system according to any one of claims 1 -5, wherein the supply sledge comprises a force-control system configured to change, responsive to a control signal (238, 338), contact forces between the contact elements (211 , 212, 311 , 312) and the direct voltage rails (209, 210, 309, 310).

7. An electric charging system according to claim 6, wherein the force-control system comprises electromagnets (235, 236) configured to press the contact elements (211 , 212) against the direct voltage rails (209, 210) in response to electric currents supplied to the electromagnets.

8. An electric charging system according to claim 7, wherein the force-control system comprises springs (238, 239) configured to detach the contact elements (211 , 212) from the direct voltage rails (209, 210) in absence of the electric currents of the electromagnets.

9. An electric charging system according to claim 7 or 8, wherein the electromagnets (235, 236) are configured act against a gravity force when pressing the contact elements (211 , 212) against the direct voltage rails (209, 210), the gravity force detaching the contact elements from the direct voltage rails in absence of the electric currents of the electromagnets.

10. An electric charging system according to claim 6, wherein the force-control system comprises a support control system (341 ) configured to control a mechanical support of the supply sledge (318) with respect to a support beam (316) and to allow, responsive to the control signal, the supply sledge to move downwards by gravity so that weight of the supply sledge is at least partly carried by the contact forces between the contact elements (311 , 312) and the direct voltage rails (309, 310).

11. An electric charging system according to any one of claims 6-10, wherein the electric charging system comprises a control system (240, 340) that is configured to carry out a loading-handshake after connecting the charging plug to the charging socket of the electric vehicle and to form the control signal (238, 338) so that the contact forces between the contact elements (211 , 212, 311 , 312) and the direct voltage rails (209, 210, 309, 310) are increased in response to the loadinghandshake and decreased after charging the electric vehicle.

12. An electric charging system according to any one of claims 1 -11 , wherein the electric charging system comprises a servomotor (130) configured to move the supply sledge along the direct voltage rails, a sensor system configured to produce sensor data indicative of a position of a front of the electric vehicle when the electric vehicle is on a charging area of the electric charging system, and a controller (161 ) configured to control the servomotor to move the supply sledge to a position determined by the sensor data.

13. An electric charging system according to claim 12, wherein the sensor system comprises one or more of following configured to detect the front of the electric vehicle: a laser sensor (132), a radio sensor, an ultrasonic sensor, a machine vision system, one or more inductor loops (133) in / on a ground of the charging area of the electric charging system.

14. An electric charging system according to any one of claims 1 -13, wherein the supply sledge comprises a cooling duct (128) configured to circulate cooling fluid to cool at least a part of the electric conductors configured to transfer the electric energy from the supply sledge to the charging plug connectable to the charging socket of the electric vehicle, and the electric charging system comprises a heatexchanger (126) configured to transfer heat away from the cooling fluid.

15. An electric charging system according to claim 14, wherein the heat-exchanger (126) is a part of the supply sledge so that the heat-exchanger and the electric conductors (113) are on opposite sides with respect to the direct voltage rails (109, 110), and thus the heat-exchanger is configured to act as at least a part of a counterweight (152) compensating for unbalance caused by weight of the electric conductors (113).

16. An electric charging system according to any one of claims 1 -15, wherein the electric charging system comprises a flexible data transfer cable (129) between the direct voltage power supply (153) and the supply sledge (118) and another data transfer cable between the supply sledge and the charging plug (114), the flexible data transfer cable folding in response to a movement of the supply sledge towards the direct voltage power supply and straightening in response to a movement of the supply sledge away from the direct voltage power supply.

17. An electric charging system according to any one of claims 1-16, wherein charging power transferable via the supply sledge is at least 200 kW18. An electric charging system according to any one of claims 1 -17, wherein, when the electric charging system is seen from above, the direct voltage rails (409) are beside a charging area occupied by the electric vehicle when the electric vehicle is being charged.

19. An electric charging system according to any one of claims 1 -17, wherein at least parts of the direct voltage rails (509) are above a charging area occupied by the electric vehicle when the electric vehicle is being charged.

20. A truck terminal comprising a direct voltage power supply system (401 , 501 ) and one or more loading docks (402-405, 502-505) each being suitable for receiving a back of an electric truck for loading and unloading goods through the back of the electric truck, wherein each of the one or more loading docks comprises an electric charging system according to any one of claims 1 -19 so that the direct voltage rails of the electric charging system are perpendicular to the loading dock and parallel with a longitudinal direction (y) of the electric truck when the electric truck is at the loading dock, and wherein the direct voltage power supply system of the truck terminal constitutes the direct voltage power supply of the electric charging system of each of the one or more loading docks.21 . A truck terminal according to claim 20, wherein a cooling system of the direct voltage power supply system (401 , 501 ) comprises an adjustable heat transfer channeling (444) switchable to a first position in which the adjustable heat transfer channeling is configured to give off heat inside a building (408, 508) of the truckterminal and to a second position in which the adjustable heat transfer channeling is configured to give off heat outside the building of the truck terminal.

22. A truck terminal according to claim 20 or 21 , wherein the direct voltage power supply system (501 ) comprises an alternating voltage-direct voltage (AC-DC) conversion system configured to transfer electric energy from an alternating current(AC) power grid to direct voltage outlets of the alternating voltage-direct voltage conversion system and a switch module (545) comprising controllable switches capable of connecting each of the direct voltage outlets to supply electric energy to the direct voltage rails of the electric charging system of any one or more of the loading docks (502-505).