A truck terminal for electric trucks

Abstract

A truck terminal for electric trucks comprises a direct voltage power supply system (101) and one or more loading docks (102) each being suitable for receiving a back of an electric truck (106) for loading and unloading goods Each loading dock comprises direct voltage rails (109) connected to the direct voltage power supply system and being bars of rigid and electrically conductive material, parallel with a longitudinal direction (y) of the electric truck at the loading dock, and a distance over the ground. Each loading dock comprises a supply sledge (118) moveable along the direct voltage rails. The supply sledge comprises contact elements 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 an electric truck.

Description

[0001] A truck terminal for electric trucks

[0002] Field

[0003] The invention relates generally to charging of electric vehicles. More particularly, 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 truck terminal comprises one or more loading docks each being suitable for receiving a back of a truck for loading and unloading goods through the back of the truck. A truck terminal for electric trucks comprises advantageously a charging system for charging batteries of electric trucks during loading and unloading goods to and from the electric trucks. Publication DE202017100795U1 describes a charging station for electric vehicles such as electric vans and electric trucks. The charging station described in DE202017100795U1 comprises a support beam which extends from a base structure in a longitudinal direction of an electric vehicle at the charging station. The support beam is horizontal and a distance over the ground. The support beam carries a charging cable so that a first part of the charging cable extends from a charging power supply system to an end of the support beam that is farthest from the base structure and a second part the charging cable extends from the above-mentioned end of the support beam to a charging plug connectable to a charging socket of an electric vehicle to supply electric energy to the electric vehicle. The second part the charging cable is mounted slidably or by means of rolling elements on a running rail installed on the support beam so that the second part the charging cable is folded when the charging plug is moved in a direction away from the base structure and straightened when the charging plug is moved in the opposite direction towards the base structure.

[0006] An inherent challenge related to charging stations of the kind described in DE202017100795U1 is that a flexible charging cable needs to be rather long. In the charging station described in DE202017100795U1 , the above-mentioned second part of the charging cable must be flexible and the length of the second part the charging cable is more than the length of the horizontal support beam. In other words, the length of the second part of the charging cable needs to be more than the maximum length of an electric vehicle at the charging station. When charging electric trucks, charging power can be on megawatt-level, which means that power losses in the charging 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 charging 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 truck terminal for electric trucks. In this document, the term “electric truck” covers not only all-electric trucks but also pluggable hybrid trucks which comprise both one or more electric motors and a combustion motor.

[0011] 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: direct voltage rails connected to the direct voltage power supply system and thus having a direct voltage therebetween and being i) bars of rigid and electrically conductive material, ii) perpendicular to the loading dock and parallel with the longitudinal direction of an electric truck when the electric truck is at the loading dock, and iii) a distance over the ground, and

[0012] - 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 truck to supply electric energy from the direct voltage rails to the electric truck.

[0013] Due to the direct voltage rails and the supply sledge moveable along the direct voltage rails, a flexible cable connected to the charging plug can be significantly shorter than e.g. a truck being charged. It is straightforward to arrange cross- sectional areas of the above-mentioned direct voltage rails to be greater than corresponding cross-sectional areas of electric conductors of a flexible cable. Thus, power losses per meter can be significantly smaller in the direct voltage rails than in a flexible cable. This is significant especially when charging power is on megawattlevel. Furthermore, the direct voltage rails can be hollow and thus liquid cooled, e.g. cooled with transformer oil or some other suitable cooling liquid.

[0014] Exemplifying and non-limiting embodiments are described in accompanied dependent claims.

[0015] 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.

[0016] 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.

[0017] The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated.

[0018] 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. Brief description of figures

[0019] 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: figure 1 a illustrates a truck terminal according to an exemplifying and non-limiting embodiment for electric trucks, figure 1 b illustrates a loading dock of the truck terminal illustrated in figure 1 a, figure 1 c illustrates a detail of the loading dock illustrated in figures 1 a and 1 b, figure 2 illustrates a detail of a loading dock of a truck terminal according to an exemplifying and non-limiting embodiment, figure 3 illustrates a detail of a loading dock of a truck terminal according to an exemplifying and non-limiting embodiment, and figures 4a and 4b illustrate a truck terminal according to an exemplifying and nonlimiting embodiment for electric trucks.

[0020] Description of exemplifying and non-limiting embodiments

[0021] 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.

[0022] Figure 1 a 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 101 and loading docks 102, 103, 104, and 105. Each of the loading docks 102-105 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 1a, an electric truck 106 is at the loading dock 102, an electric truck 107 is at the loading dock 104, and the loading docks 103 and 105 are empty. Each of the loading docks 102-105 comprises direct voltage rails a distance over the ground and connected to the direct voltage power supply system 101 and thus having a direct voltage therebetween. The direct voltage rails are bars of rigid and electrically conductive material, e.g. copper, and perpendicular to the loading dock and parallel with the longitudinal direction of an electric truck when the electric truck is at the loading dock. In figure 1 a, the longitudinal direction of the electric trucks 106 and 107 is parallel with the y-axis of a coordinate system 199. Furthermore, each of the loading docks 102-105 comprises a supply sledge that is moveable along the direct voltage rails of the loading dock. In figure 1 a, the supply sledge of the loading dock 102 is denoted with a reference 118. In this exemplifying case, each of the loading docks 102-105 comprises a support beam perpendicular to the loading dock and parallel with the longitudinal direction of the electric truck when the electric truck is at the loading dock. The direct voltage rails of the loading dock are mechanically attached to the support beam with the aid of electric insulator elements. In figure 1 a, the support beam of the loading dock 102 is denoted with a reference 116.

[0023] In the exemplifying truck terminal illustrated in figure 1 a, the direct voltage power supply system 101 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 1 a. 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 the building 108, 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. The charging power available at each of the loading docks 102-105 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 direct voltage rail 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 xW8fim, 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 in the direct voltage rail 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 0.1 m x i 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.

[0024] Figure 1 b shows a schematic side view of the loading dock 102 of the truck terminal illustrated in figure 1 a. The viewing direction related to figure 1 b is illustrated by the coordinate system 199. Figure 1 c 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 b, and the geometric section plane is parallel with the xz-plane of the coordinate system 199. In figure 1c, the cross-sections of the direct voltage rails of the loading dock 102 are denoted with references 109 and 110, and the electric insulator elements mechanically supporting the direct voltage rails with respect to the support beam 116 are denoted with a reference 117. In this exemplifying case, the support beam 116 is an I-beam as shown in figure 1 c. 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. As shown in figure 1 c, a middle part

[0025] 150 of the I-beam is between the direct voltage rails 109 and 110, and side parts

[0026] 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. The support beam 116 is advantageously connected to the ground potential as it is schematically shown in figure 1 b. Thus, there is no direct route for a short circuit arc between the direct voltage rails 109 and 110. 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 horizontal direct voltage rail can be vertically or obliquely above another horizontal direct voltage rail. In the exemplifying case illustrated in figure 1 b, there are vertical beams 160 configured to sustain the support beam 116. The vertical beams 160 are advantageously as near as possible to a building 108 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.

[0027] 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 of an electric truck to supply electric energy from the direct voltage rails 109 and 110 to the electric truck. In figure 1 b, the charging socket of the electric truck 106 is denoted with a reference 115.

[0028] In the exemplifying supply sledge 118 illustrated in figure 1 c, the above-mentioned 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 connectable to a charging socket of an electric truck. 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 truck 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.

[0029] The exemplifying supply sledge 118 illustrated in figure 1c 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 c, 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 c, the direct voltage rails 109 and 110 have longitudinal 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.

[0030] In a truck terminal according to an exemplifying and non-limiting embodiment, each of the loading docks 102-105 comprises a sensor system configured to produce sensor data indicative of a position of the front of an electric truck when the electric truck is at the loading dock under consideration. 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 an area occupied by an electric truck when the electric truck is at the loading dock. In figure 1 b, 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.

[0031] The exemplifying supply sledge 118 illustrated in figure 1 c 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 c, 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 1c 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 c to prevent tilting of the supply sledge 118. In the exemplifying case illustrated in figure 1 c, 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. The position can be e.g. 1 -3 meters backwards from the position of the front of the electric truck.

[0032] 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.

[0033] In a truck terminal according to an exemplifying and non-limiting embodiment, the loading dock that comprises the supply sledge 218 comprises 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 truck 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 loadinghandshake and decreased after charging the electric truck. 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 truck. 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 a cockpit of an electric truck, 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 truck, 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.

[0034] To carry out the above-mentioned 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 system. The exemplifying loading dock 102 illustrated in figure 1 b comprises a flexible data transfer cable 129 between the direct voltage power supply system 101 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 c. The flexible data transfer cable 129 is folded in response to a movement of the supply sledge 118 towards the direct voltage power supply system 101 and is straightened in response to a movement of the supply sledge 118 away from the direct voltage power supply system 101. 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 1 18. 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.

[0036] 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 loading dock 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 truck 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 truck. 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 truck.

[0037] In the exemplifying truck terminal illustrated in figure 1 a, 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 1 a. Figure 4a 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 402, 403, 404, and 405 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 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. 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 a coordinate system 499. In figure 4b, one of the direct voltage rails of the loading dock 402 is denoted with a reference 409, a support beam of the loading dock 402 is denoted with a reference 416, a supply sledge of the loading dock 402 is denoted with a reference 418, a charging plug is denoted with a reference 414, and a charging socket of the electric truck 406 is denoted with a reference 415. In the exemplifying loading dock 402 illustrated in figure 4b, there is a cable 421 that is flexible such that the supply sledge 418 can be above the electric truck 406.

[0038] In the exemplifying truck terminal illustrated in figure 1 a, a cooling system of the direct voltage power supply system 101 comprises an adjustable heat transfer channeling 144 switchable to a first position in which the adjustable heat transfer channeling is configured to give off heat inside the building 108 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 108 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 101 are wanted to be used for warming up the building 108 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 108. 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.

[0039] The above-mentioned cooling system can be for example a liquid cooling system in which case the adjustable heat transfer channeling 144 is a liquid circulation channeling, a heatsink 142 inside the building 108 can be a heat exchanger as well as a heatsink 143 outside the building 108 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 144 can be a flow-through channeling, the heatsink 142 inside the building 108 can be simply an open end of a channel for blowing warm cooling air into the interior of the building 108, and correspondingly the heatsink 143 outside the building 108 can be simply an open end of a channel for blowing warm cooling air to the ambient air outside the building 108. In the exemplifying truck terminal illustrated in figure 1a, the AC-DC converters of the direct voltage power supply system 101 are located inside the building 108. 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 144, but which is emitted to surroundings through e.g. casings of the AC-DC converters warms up the building 108.

[0040] In the exemplifying truck terminal illustrated in figure 4a, a direct voltage power supply system 401 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 408 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 408. In the exemplifying truck terminal illustrated in figure 4a, the AC-DC converters of the direct voltage power supply system 401 are located outside the building 408. 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 408.

[0041] In the exemplifying truck terminal illustrated in figure 4a, the direct voltage power supply system 401 comprises a switch module 445 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 402-405. 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 402-405. The AC-DC converters shown in figure 4a 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 401 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 402-405. Thus, different AC-DC conversion systems are possible for supplying electric energy from an AC power 450 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.

[0042] In the exemplifying case illustrated in figure 4a, the switch module 445 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.

[0043] 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. A truck terminal for electric trucks, the truck terminal comprising a direct voltage power supply system (101 , 401 ) and one or more loading docks (102-105, 402-405) each being suitable for receiving a back of an electric truck for loading and unloading goods through the back of the electric truck, characterized in that each of the one or more loading docks comprises:- direct voltage rails (109, 110, 209, 210, 309, 310, 409) connected to the direct voltage power supply system and thus having a direct voltage therebetween and being i) bars of rigid and electrically conductive material, ii) 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 iii) a distance over ground, and- a supply sledge (118, 218, 318, 418) 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, 414) galvanically connected to the electric conductors and connectable to a charging socket of the electric truck to supply electric energy from the direct voltage rails to the electric truck.

2. A truck terminal according to claim 1 , wherein each of the loading docks comprises a support beam (116) perpendicular to the loading dock and parallel with the longitudinal direction of the electric truck when the electric truck is at the loading dock, and electric insulator elements (117) configured to mechanically support the direct voltage rails with respect to the support beam.

3. A truck terminal according to claim 2, wherein the support beam is galvanically connected to ground potential.

4. A truck terminal 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. A truck terminal 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 perpendicular to the side parts (151 ).

6. A truck terminal according to any one of claims 1 -5, wherein the electric conductors (113) of the supply sledge (118) 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) 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 (114) connectable to the charging socket of the electric truck.

7. A truck terminal according to any one of claims 1 -6, 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).

8. A truck terminal according to claim 7, 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.

9. A truck terminal according to claim 8, 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.

10. A truck terminal according to claim 8 or 9, 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.

11. A truck terminal according to claim 7, 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).

12. A truck terminal according to any one of claims 7-11 , wherein each of the one or more loading docks 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 truck 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 truck.

13. A truck terminal according to any one of claims 1 -12, wherein each of the one or more loading docks 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 truck when the electric truck is at the loading dock, and a controller (161 ) configured to control the servomotor to move the supply sledge to a position determined by the sensor data.

14. A truck terminal according to claim 13, wherein the sensor system comprises one or more of following configured to detect the front of the electric truck: 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 an area occupied by the electric truck when the electric truck is at the loading dock.

15. A truck terminal according to any one of claims 1 -14, 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 truck, and the truck terminal comprises one or more heat-exchangers (126) configured to transfer heat away from the cooling fluid.

16. A truck terminal according to claim 15, wherein the supply sledge (118) comprises one of the one or more the heat-exchangers (126) so that the heatexchanger (126) of the supply sledge and the electric conductors (113) of the supply sledge are on opposite sides with respect to the direct voltage rails (109, 110), and thus the heat-exchanger of the supply sledge is configured to act as at least a part of a counterweight (152) compensating for unbalance caused by weight of the electric conductors (113) of the supply sledge.

17. A truck terminal according to any one of claims 1 -16, wherein each of the one or more loading docks comprises a flexible data transfer cable (129) between the direct voltage power supply system (101 ) and the supply sledge (118) of the loading dock 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 system and straightening in response to a movement of the supply sledge away from the direct voltage power supply system.

18. A truck terminal according to any one of claims 1 -17, wherein charging power of each of the one or more loading docks is at least 200 kW.

19. A truck terminal according to any one of claims 1 -18, wherein, when the loading dock (102-105) is seen from above, the direct voltage rails are beside an area occupied by the electric truck when the electric truck is at the loading dock.

20. A truck terminal according to any one of claims 1 -18, wherein at least parts of the direct voltage rails are above an area occupied by the electric truck when the electric truck is at the loading dock (402-405).21 . A truck terminal according to any one of claims 1 -20, wherein a cooling system of the direct voltage power supply system (101 , 401 ) comprises an adjustable heat transfer channeling (144) switchable to a first position in which the adjustable heat transfer channeling is configured to give off heat inside a building (108, 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 of the truck terminal.

22. A truck terminal according to any one of claims 1 -21 , wherein the direct voltage power supply system (401 ) 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 (445) comprising controllable switches capable of connecting each of the direct voltage outlets to supply electric energy to the direct voltage rails of any one or more of the loading docks (402-405).