Charging electric vehicles

Abstract

An electric vehicle charging station comprising a housing (102, Fig. 4), a DC power supply (103, Fig 1), a cable 104 for supplying the direct current to a vehicle (101, Fig. 1), a storage region (402,

Description

Systems for the rapid charging of electric vehicles are well known, with deployment taking place in many countries in anticipation of an increasing use of electric vehicles. Electric vehicles can be recharged from conventional mains supplies, typically at a power level of 3.5 kW, if being charged from a conventional socket, or at 7 kW if being charged from a dedicated unit. Charging takes place over several hours, possibly overnight. Rapid charging systems aim to provide typically eighty percent of a full charge within a charging period of less than thirty minutes. To achieve this, it is necessary to provide a charging cable connectable to an electric vehicle that is capable of conveying a relatively high current, typically in excess of one hundred amps. The cable terminates in a charging plug which is inserted into a socket forming part of the vehicle. In most systems of this type, holsters are provided for supporting these plugs when the charging system is not in use. However, unlike petrol pumps that terminate with a metal nozzle, it is not necessary for the plug to be returned to the holster at the end of a charging session. As a result of this, situations have been identified where charging plugs have been dropped which in turn may result in plug damage and early plug replacement at a significant cost to the operator. A further problem arises with unsecured cables in that it is also possible for them to present a trip hazard and as such it is undesirable for the cables to be left on the floor between charging sessions. Situations have also been identified where cables have been cut and stolen. Thus, for all of these reasons, it is desirable to provide a system in which the cable retracts into a housing after a charging operation has been completed. A possible solution is presented in GB 2 608 589 assigned to the present applicant. In this known system, the cable is retracted by being wound onto a reel. A relatively flexible cable is required and to allow the required rotational movement, it is necessary to provide slip rings to facilitate the transmission of charging current and also to facilitate the transmission of data between the vehicle and the charging system. It has been appreciated that the use of slip rings while transmitting charging current generates electrical noise, therefore the unwinding of the cable is completed and a data exchange takes place before charging is initiated. However, under these circumstances, charging current passes through the slip rings while they are stationary; whereas most slip rings are designed to be moving rotationally while current transfer takes place, thereby evenly distributing wear upon the rings due to the transmission of current. Consequently, problems have been identified in terms of using this approach, particularly within rapid charging systems. According to a first aspect of the present invention, there is provided an apparatus for charging electric vehicles, comprising: a housing; a supply of direct current charging electricity; a cable for supplying said direct current charging electricity to an electric vehicle at a power level that is significantly higher than that available from a standard mains supply; a storage region within said housing for storing a proportion of said cable when not in use, wherein said storage region has a depth sufficient to receive said cable while preventing lateral movement of said cable; a first roller arranged to be driven by an electric motor; a second adjustable roller arrange to force the cable against said first roller to facilitate extraction and retraction of the cable from the storage region; and a cable guide within the storage region arranged to deflect a retracting cable to ensure the repeatable folding of said cable as said cable is retracted into the storage region. In an embodiment the storage region is defined by a container receivable within the housing and the cable may enter the container via an orifice in the housing. The first roller and the second adjustable roller may be supported by the container. In an embodiment the apparatus includes a rechargeable battery for supplying the direct current charging electricity. The apparatus may have a rectifying device which receives alternating current from a standard mains supply and recharges the rechargeable battery. The apparatus may have means for generating power from one or more renewable sources, wherein the rechargeable battery receives direct current charging electricity from these renewable sources. In an embodiment the cable is constructed from a plurality of insulated conductors to provide a sufficient cross-sectional area for the level of direct current being supplied while achieving sufficient flexibility to facilitate the storage of said cable. The cable may be of a type designed to minimise magnetic field generation. According to a second aspect of the present invention, there is provided a method of charging electric vehicles, comprising the steps of: extracting a cable from a housing, in which said cable is connected to a supply of direct current electricity; connecting the cable to an electric vehicle to perform a charging procedure; disconnecting the cable from the electric vehicle after the charging procedure at a power level that is significantly higher than that available from a standard mains supply; and retracting the cable back into the housing, wherein: the housing includes a storage region for storing a proportion of the cable when not in use; the storage region has a depth sufficient to receive the cable while preventing lateral movement of the cable; and the storage region comprises a first roller arranged to be driven by an electric motor, a second adjustable roller arranged to force the cable against the first roller to facilitate said extracting step and said retracting step, and a cable guide to deflect the charging cable to ensure repeatable folding of the cable as the cable is retracted into the storage region. Embodiments of the invention will be described, by way of example only, with reference to the accompanying drawings. The detailed embodiments show the best mode known to the inventor and provide support for the invention as claimed. However, they are only exemplary and should not be used to interpret or limit the scope of the claims. Their purpose is to provide a teaching to those skilled in the art. Components and processes distinguished by ordinal phrases such as “first” and “second” do not necessarily define an order or ranking of any sort. In the drawings: Figure 1 shows an environment for charging an electric vehicle; Figure 2 shows a schematic representation of the apparatus for charging electric vehicles identified in Figure 1; Figure 3 shows operations performed by a microcontroller identified in Figure 2; Figure 4 the rear of a housing identified in Figure 7; Figure 5 shows an example of a container for insertion within a storage region identified in Figure 4; Figure 6 illustrate a fully extracted charging cable; Figure 7 shows partial retraction of the charging cable; and Figure 8 shows full retraction of the charging cable. Figure 1 An environment for charging an electric vehicle 101 is shown in Figure 1. A housing 102 houses an apparatus for charging electric vehicles. The apparatus receives a supply 103 of direct current charging electricity and includes a cable 104 for supplying the direct current charging electricity to the electric vehicle 101. In this embodiment, the supply of direct current electricity is supplied at a first power level that is significantly higher than that available from a standard mains supply. It may therefore be identified as a rapid charging system. The charging apparatus may receive electrical power direct from a national grid, with the power level supplied being of a sufficient magnitude to achieve rapid charging. Furthermore, in some installations, it is possible for several charging systems of this type to be provided. However, this assumes that it is possible to receive sufficient electrical power from a grid supply dedicated for this particular purpose. In other situations, the level of power available for the grid may be significantly lower, or even non-existent. To facilitate rapid charging under such circumstances, the environment of Figure 1 includes a rechargeable battery 105 and the direct current charging electricity for the vehicle is supplied from this rechargeable battery. In an embodiment, the environment may also include a rectifying device 106 that receives alternating current from a standard mains supply which is in turn used to recharge the rechargeable battery 105 at a second power level, wherein the second power level is significantly lower than the first power level. Under these circumstances the charging of battery 105 is relatively slow but the charging of the vehicle 101 from the battery 105 is relatively rapid. In an embodiment, the system also includes means for generating power from one or more renewable sources which, in the example shown in Figure 1, includes a wind turbine 107 and solar panels 108. The rectifying device 106 includes appropriate inverters and conditioners for converting electricity received from the wind turbine 107 and the solar panels 108 into direct current at an appropriate voltage for recharging the battery 105 or directly charging the vehicle 101. When the system is connected to a mains supply, it is accepted practice for the vehicle 101 to be charged or the battery 105 to be charged, with the mains source being disconnected if charge is being received from the battery 105. In an embodiment, the cable 104 is constructed from a plurality of insulating conductors to provide a sufficient cross-sectional area for the level of direct current being supplied, while achieving sufficient flexibility to facilitate the storage of the cable. In an embodiment, the cable is of a type designed to minimise magnetic field generation. Cables of this type are available from Green ELMF Cables Limited and the underlying technology is described in US 6,506,971. These cables are primarily designed for conveying alternating currents, with the emphasis being on minimising the generation of magnetic fields. However, it has been appreciated that cables of this type may also be deployed for direct current charging where the technology, primarily intended for reducing magnetic fields, also presents an enhanced mechanical attribute in that the cable is relatively flexible compared to cables traditionally used for the charging of electric vehicles. The apparatus also includes a touchscreen 109 for displaying information to a user and for receiving commands from the user. The apparatus may also include a card reader 110 to receive payment or authorisation before a charging session is initiated. Figure 2 A schematic representation of the apparatus for charging electric vehicles and contained within the housing 102, is shown in Figure 2. The supply cable 103 is supplied to a contactor 201 and the charging cable 104 extends from an output of the contactor 201. Operation of the contactor 201 is controlled by a microcontroller 202. The microcontroller 202 also controls the operation of a brake 203 and the operation of a drive motor 204. In addition, the microcontroller 202 also receives input data from a movement detector 205. Figure 3 Operations performed by the microcontroller 202 are shown in Figure 3. At step 301, the microcontroller interacts with a user to initiate a charging session. Information is displayed to the user on the touchscreen 109 which in turn conveys instructions back to the microcontroller in response to manual interactions. In addition to acknowledging a request to charge a vehicle, authorisation measures may also be taken which may involve receiving payment by an appropriate card or recording details of a charging operation for subsequent billing. Ultimately, these interactions result in the microcontroller acknowledging that a charging operation may take place. Thus, it is now possible for a charging plug to be inserted into an appropriate charging socket of an electric vehicle. In an embodiment, the touchscreen 109 invites the user to manually retract the cable. At step 302, the microcontroller 202 instructs the brake 203 to release the cable so that it may be retracted. The movement detector 205 then detects that force has been applied to the charging cable 104 and this data is notified to the microcontroller 202 such that it detects manual extraction at step 303. In response to detecting the manual extraction (or at least an attempt to manually extract the cable) the motor 204 is energised at step 304. The user may continue to manually extract the cable, which now feels relatively easy, such that it facilitates the plugging of the charging plug into the charging socket of the electric vehicle. At step 305, data communication takes place with the electric vehicle in accordance with standard vehicle charging protocols. If a problem is identified at this stage, an appropriate message is displayed on the touchscreen 109 and charging is inhibited. However, under normal circumstances, it should now be possible to charge the vehicle. In this embodiment, the brake 203 is again engaged at step 306 and vehicle charging takes place at step 307. In an embodiment, the touchscreen 109 shows the status of the charging procedure and may identify the level of current that is being supplied to the vehicle. The touchscreen 109 will then notify the user to the effect that the charging session has completed and invite the user to remove the charging plug. Upon detecting a disconnection at step 308, the brake 203 is released and the charging cable 104 is retracted at step 310. When fully retracted, the brake 203 is again engaged at step 311 and a question is then asked at step 312 as to whether the apparatus is to continue in service. When answered in the affirmative, control is returned to step 301 in anticipation of receiving the next user interaction. The question asked at step 312 may be answered in the negative in anticipation of a servicing operation or, in an embodiment, during periods when it is necessary to recharge the battery 105. Figure 4 The rear of housing 102 is shown in Figure 4. A side panel includes an opening 401 allowing the charging cable 104 to be retracted from the housing 102. The housing 102 defines a storage region 402 for storing a proportion of the charging cable when not in use. In this embodiment, the charging cable is supported within a container, described with reference to Figure 5. The container has a width that is compatible with the internal width 403 of the storage region and a height that is substantially half the height 404 of the storage region. The container has a depth sufficient to receive the charging cable while preventing lateral movement of the cable. Thus, the container has a depth internally that is only slightly larger than the diameter of the charging cable such that, during the retraction and storage of the cable, it is not possible for the cable to move in a lateral direction, thereby preventing creasing and snagging of the cable. After installation of the container within the storage region 402, a rear door 405 is secured by means of a locking mechanism 406. Figure 5 An example of a container 501 for insertion within the storage region 402 is shown in Figure 5. A first roller 502 is arranged to be driven by the electric motor 204. A second adjustable roller 503 is arranged to force the charging cable against the first roller to facilitate extraction and retraction of the charging cable 104 from the storage region 402 and back into the storage region 402. A first cable guide roller 504 within the container 501 is arranged to ensure the repeatable folding of the charging cable 104 as the charging cable is retracted into the storage region. A second cable guide roller 505 is also provided for directing the charging cable 104 downwards during the retraction operation. Figure 6 A fully extracted charging cable 104 is shown in Figure 6. The charging cable 104 exits the container 501 via a first vertical roller 601, and an opposing second vertical roller behind the first vertical roller 601 shown in Figure 6. In the configuration shown in Figure 6, vehicle charging is performed at step 307 until disconnection is detected at step 308. When present, the brake is released at step 309 and cable retraction is initiated at step 310. Figure 7 Cable retraction is performed by rotation of the first roller 502, driven by the electric motor 204. As shown in Figure 7, this forces the charging cable 104 towards the bottom of the frame 501 in the direction of a first arrow 701. In the condition shown in Figure 7, a significant proportion of the charging cable 104 has been retained within the storage region 402. However, for most practical applications, this does not represent a sufficient length of cable. Further retraction is made possible by folding the cable and the embodiment provides for the repeatable folding of the cable in a predictable way as it is retracted into the storage region; with the actual storage region now being defined by the internal volume of the container 501 receivable within the housing. In this embodiment, the first roller 502 and the second adjustable roller 503 are supported by the container 501. The container 501 also supports the first cable guide roller 504 and the second cable guide roller 505. As shown in Figure 7, the first cable guide roller 504 deflects the retracting charging cable 104 in the direction of a second arrow 702. This first cable guide roller therefore ensures the repeatable folding of the charging cable 104 each time this cable is retracted into the storage region. Figure 8 Further retraction of the vehicle charging cable 104 into the container 501 is shown in Figure 8. As described with reference to Figure 7, the first cable guide roller 504 has introduced a bend into the retracted cable 104, such that further retraction of the charging cable 104 results in further folding in the direction of the second arrow 702. Thus, as illustrated in Figure 8, this results in a complete internal bend 801 being formed in the charging cable 104, thereby significantly increasing the length of charging cable that may be retained within the container; which is itself held within the storage region. Given this configuration, it is now possible for a practical length of charging cable to be retained within the storage region when not in use. Thus, in this way, the charging of an electric vehicle may be conducted in a conventional manner but, after the charging operation has been completed, full retraction of the cable ensures that the charging plug cannot be damaged, the charging cable does not present a trip hazard and the charging cable cannot be cut from the charging apparatus. The apparatus therefore presents a method of charging electric vehicles by extracting a cable from a housing, in which the cable is connected to a supply of direct-current electricity. The cable is connected to an electric vehicle to perform a charging procedure and then disconnected from the electric vehicle after the charging procedure, whereupon the cable is retracted back into the housing. The housing 102 includes a storage region 402 that has a 5 depth sufficient to receive the cable while preventing lateral movement of the cable; lateral movement being perpendicular to the plane of Figure 8. The storage region has a first roller 502 arranged to be driven by an electric motor 204, along with a second adjustable roller 503 arranged to force the cable against the first roller 502 to facilitate the extracting step and the 10 retracting step. In addition, a cable guide 504 is provided to ensure repeatable folding of the cable as the cable is retracted into the storage region.

Claims

1. An apparatus for charging electric vehicles, comprising:a housing;a supply of direct current charging electricity;a cable for supplying said direct current charging electricity to an electric vehicle at a power level that is significantly higher than that available from a standard mains supply;a storage region within said housing for storing a proportion of said cable when not in use, wherein said storage region has a depth sufficient to receive said cable while preventing lateral movement of said cable;a first roller arranged to be driven by an electric motor;a second adjustable roller arrange to force the cable against said first roller to facilitate extraction and retraction of the cable from the storage region; anda cable guide within the storage region arranged to deflect a retracting cable to ensure the repeatable folding of said cable as said cable is retracted into the storage region.

2. The apparatus of claim 1, wherein said storage region is defined by a container receivable within the housing.

3. The apparatus of claim 2, wherein the cable enters the container via an orifice in the housing.

4. The apparatus of claim 2 or claim 3, wherein the first roller and the second adjustable roller are supported by said container.

5. The apparatus of any of claims 1 to 4, including a rechargeable battery, wherein said direct current charging electricity is supplied from said rechargeable battery.

6. The apparatus of claim 5, comprising a rectifying device, wherein said rectifying device receives alternating current from a standard mains supply and recharges the rechargeable battery.

7. The apparatus of claim 5, comprising means for generating power from one or more renewable sources, wherein said rechargeable battery receives direct current charging electricity from said one or more renewable sources.

8. The apparatus of any of claims 1 to 7, wherein said cable is constructed from a plurality of insulated conductors to provide a sufficient cross-sectional area for the level of direct current being supplied while achieving sufficient flexibility to facilitate the storage of said cable.

9. The apparatus of claim 8, wherein said cable is of a type designed to minimise magnetic field generation.

10. A method of charging electric vehicles, comprising the steps of: extracting a cable from a housing, in which said cable is connected to a supply of direct current electricity;connecting the cable to an electric vehicle to perform a charging procedure;disconnecting the cable from the electric vehicle after the charging procedure at a power level that is significantly higher than that available from a standard mains supply; andretracting the cable back into the housing, wherein:the housing includes a storage region for storing a proportion of the cable when not in use;the storage region has a depth sufficient to receive the cable while preventing lateral movement of the cable; andthe storage region comprises a first roller arranged to be driven by anelectric motor, a second adjustable roller arranged to force the cable against the first roller to facilitate said extracting step and said retracting step, and a cable guide to deflect the charging cable to ensure repeatable folding of the cable as the cable is retracted into the storage region.

11. The method of claim 10, wherein the storage region is defined by a container receivable within the housing.

12. The method of claim 11, wherein the cable enters the container via an orifice in the housing during said retracting step.

13. The method of any of claims 10 to 12, wherein the first roller and the second adjustable roller are supported by the container.

14. The method of any of claims 10 to 13, further comprising the step of receiving the direct current charging electricity from a rechargeable battery.

15. The method of claim 16, further comprising the step of recharging the battery from a standard mains supply.

16. The apparatus of claim 14, further comprising the steps of: generating power by means of one or more renewable sources; and recharging the battery from the one or more renewable sources.

17. The apparatus of any of claims 10 to 16, wherein said cable is constructed from a plurality of insulated conductors to provide a sufficient cross-sectional area for the level of direct current being supplied while achieving sufficient flexibility to facilitate the storage of said cable.

18. The apparatus of claim 17, wherein said cable is of a type designed to minimise magnetic field generation.

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