GB2597740A

GB2597740A - Electrical Vehicle charging system

Info

Publication number: GB2597740A
Application number: GB2011980.6A
Authority: GB
Inventors: White Simon; Weston Paul
Original assignee: Siemens Mobility Ltd
Current assignee: Siemens Mobility Ltd
Priority date: 2020-07-31
Filing date: 2020-07-31
Publication date: 2022-02-09
Also published as: WO2022023563A1; GB202011980D0; GB2603739A

Abstract

An electric vehicle (EV) charging system includes a central control module 1 and at least one local charging module 18, remote from the central control module, to supply electricity to an EV 19. The central control module receives electricity from a power distribution network and distributes electricity to at least one local charging feed. The central control module includes at least one central switch, and a central controller in communication with a communication network. Each central switch is coupled exclusively to one of the local charging feeds and is switched by the central controller on receipt of an authorisation signal transmitted to the central controller via the communications network. The local charging module(s) includes a local controller, configured to be activated by the switching of the central switch coupled to one local charging feed. The local charging module also includes: a charging outlet 23 that connects to an EV; and a local switch, coupled to the outlet, and switched by the local controller. The local charging module may be mounted in, and the local charging feed housed in, a cabling infrastructure element which provides a dedicated infrastructure for the EV charging system and which may be adapted to fit between conventional infrastructure elements (e.g. kerbs (curbs) of a pathway).

Description

Intellectual Property Office Application No G132011980.6 RTM Date:26 January 2021 The following terms are registered trade marks and should be read as such wherever they occur in this document: Ubitricity Char.gy Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo

ELECTRIC VEHICLE CHARGING SYSTEM

The present invention relates to an electric vehicle charging system, in particular a charging system comprising a central control module adapted to receive electricity from a power distribution network and to distribute electricity to at least one local distribution feed.

As part of a move towards achieving a low or net zero carbon target globally by 2050 the driving of electric vehicles (EV) has been actively promoted. For example, in the United Kingdom it is planned, over the next twenty years, to encourage drivers to adopt the use of EVs in preference to conventional petrol and diesel vehicles that rely on inter- nal combustion engines (ICE) as a means of reducing emissions, particularly in built up areas. Since each EV requires charging to enable this mass adoption of low-emission vehicles an appropriate charging infrastructure must either be in place or easily installed. For vehicles that spend the majority of time parked at an owner's property charging facili- ties can be provided on-site at the property. This is advantageous as it allows the charg-ing of EVs at night, which is convenient for both the owner and the power supplier, since charging at night has a reduced impact on the local electrical supply grid compared with daytime charging, and EVs can charge using a low current over a period of several hours. This solution is ideal where a property has sufficient land (such as a drive or garage) for the EV to be connected to the owner's power supply. However, where vehicle owners are reliant on on-street or communal parking this solution is less attractive. Aside from issues relating to the availability of charging facilities, charging an EV from a domestic property with a cable trailing across a footway or street to reach the vehicle is typically not permitted, and at the very least, poses a significant health and safety hazard. In the United Kingdom a housing stock survey from 2010 estimated that 32% of the population were reliant on on-street parking, which creates an issue in enabling this group in accessing EV charging facilities, and in reducing vehicle emissions generally.

Figure 1 illustrates a schematic block diagram of a conventional electric vehicle charging system. The EV charger 100 comprises a microcontroller module 101 able to receive communications via a 3G/4G/5G enabled device 102 in communication with a communications network 103. Authorisation and payment functions to enable a user to charge an EV are carried out at a backoffice 104 using the Open Charge Point Protocol (OCPP) communications standard. The microcontroller module 101 is connected to a user module 105, comprising a payment system, such as an RFID/NFC (Radio Frequency Identification Device/Near-Field Communication) reader 106, a user display or touch sensitive screen 107, and user input switches or keypad 108 if the screen is not touch sensitive.

The microcontroller module 101 also links to a meter 109 that records the electricity usage during charging, the meter being MID (Measurement Instruments Directive) certified, and a power contactor 110 that is enabled to supply current to the outlet connector 111 that connects to the EV. A locking mechanism 112 is provided, coupled to the outlet con- 1 0 nector 111 and also under the control of the microcontroller module 101 to prevent un- authorised disconnection and disconnection during charging. If disconnection is not prevented there is a risk of an arc being generated on removal of the outlet connector, which is both damaging to the connector contacts and hazardous to health. In order to supply current to an EV the meter 109 is coupled to a power distribution network 112 via a pow- er inlet 113 (either single-or three-phase), a manual isolator 114 and a 30mA type B re-sidual current breaker (RCD) 115. Each EV charger is provided with a TT earth spike or earthing mat (not shown).

In use, a user initiates charging by presenting an RFID card provided by the EV charging system network operator to the RFID/NFC reader 106. The EV charger checks this card against a centralised database housed at the backoffice 104 to authenticate the user and commence charging. Alternatively a smartphone or other smart device may be used to initiate the charge using an app installed on the device by communicating with the backoffice 104 directly via a communications network or by using RFID or NEC communications inherent in the smartphone/device with the RFID/NFC reader 106.

Whilst such EV chargers are acceptable for deployment individually or in clusters in car parks, for example, they are not ideal for deployment in on-street situations, such as in urban areas. Such EV chargers are bulky, since they must include an enclosure for housing all of the hardware elements that provide their function, relatively high cost due to this bulk and the complexity of the hardware they contain, and given their need for a TT earth spike, require the earth spike to be driven 2m into the ground or an earth mat buried in their vicinity nearby to function. Such factors are either undesirable or unattainable in a typical built-up urban setting, where typically space is at a premium. Home EV charging units however differ in that authentication and metering are not required, and consequently are lower in cost than publicly available EV chargers. Me-tering (for example, via the electricity meter already installed in a property), security and installation are the responsibility of the homeowner, but this requires adequate land adjacent a property to park a vehicle during charging. Consequently this is not suitable for on-street parking locations.

One solution to this issue that has been proposed previously is to use street light- 1 0 ing columns to provide power and to access this using an intelligent charging cable. This cable provides the communications, power control switch, energy meter and earth leakage safety device of the EV charger 100 as an inline module within a charging cable. A user plugs the intelligent cable into a purpose provided socket in the street lighting column, and their EV charging provide bills them appropriately for electricity used. Such systems are provided by Ubitricity (htips://www.iibitric:ty.conVeni) and Char.gy (littps://char.gy/). Although such systems are attractive for on-street parking locations, they require modification of the lighting column or bollard to accommodate the electrical outlet and additional electronics. Lighting columns are typically provided with a TN-C-S earthing system, rather than then earthing system required by EV chargers, and as such this also requires modification. In the United Kingdom at least a further issue is present in that local authorities generally install lighting columns away from the edge of the road and towards the back of the footway, meaning that charging cables would need to be draped across the footway to enable on-street charging. Furthermore, in towns and cities where wall-mounted lighting is used, there is no lighting column available to act as the EV charger enclosure. Consequently there is a need for an EV charging solution that can be employed easily in on-street parking locations and that offers greater flexibility in terms of cost and installation than conventional systems.

The present invention aims to address these issues by providing, in a first aspect, an electric vehicle charging system comprising: a central control module adapted to re-ceive electricity from a power distribution network and to distribute electricity to at least one local charging feed, comprising: at least one central switch, each central switch cou-pled exclusively to one of the at least one local charging feeds; and a central controller in communication with a communications network; wherein each central switch is adapted to be switched by the central controller on receipt of an authorisation signal transmitted to the central controller via the communications network; and at least one local charging module, remote from the central control module, and adapted to receive electricity from at least one of the local charging feeds and to supply electricity to an electric vehicle, comprising: a local controller configured to be activated by the switching of the central switch coupled to one local charging feed; an outlet adapted to connect to an electric vehicle; and a local switch adapted to be switched by the local controller and coupled to the outlet.

The present invention offers the advantages that the metering and authentication functions are separated from the charging unit that is plugged into a vehicle, thus reducing cost and complexity of components. In addition, by removing the bulky hardware required to contain metering and authentication devices from the location at which an electric vehicle is charged and using instead a local charging module mounted on or in a post without a local TT earth the electric vehicle charging system of embodiments of the present invention can be installed easily in built up urban environments to provide on-street charging.

Preferably, the local controller is adapted to communicate with the electric vehi-2 0 cle.

Preferably, the local charging feed is connected to the local charging module by a switched line Li, a neutral line N and a protective earth line PE. Alternatively, the local charging feed is connected to the local charging module by a switched line Ll, a neutral line N, a protective earth line PE and a live support line LS. Preferably, the local charging module further comprises a power supply unit coupled to the live support line LS and the neutral line N and adapted to power the local controller.

Preferably, the central control module is coupled to a plurality of local charging feeds, and wherein each local charging feed is coupled to at least one local charging module.

Preferably, the central controller is adapted to control each central switch inde-pendently.

Preferably, the central control module further comprises a meter adapted to record the flow of electricity to each local charging feed.

Preferably, the central controller is adapted to communicate with at least one of a user and an authorisation system for electric vehicle charging.

Preferably, the local charging module further comprises a second local charging feed and a second charging outlet adapted to connect to a second electric vehicle. Preferably, the local charging feed comprises cabling having a minimum cross-sectional area as determined by the voltage drop over its length. In this situation, the central control module may be coupled to a first local charging feed having a first cross-sectional area and a second local charging feed having a second cross-sectional ar-ea, wherein the first cross-sectional area is less than the second cross-sectional area. Preferably, the local charging module is mounted in, and the local charging feed is housed in, a cabling infrastructure element. More preferably, the cabling infrastructure element provides a dedicated infrastructure for the electric vehicle charging system. The cabling infrastructure element may house a cabling conduit through which the local charging feed passes. Preferably, the cabling infrastructure element is adapted to fit between a first and a second conventional infrastructure element.

The present invention will now be described by way of example only, and with reference to the accompanying drawings, in which: Figure 1 illustrates a schematic block diagram of a conventional electric vehicle charging system; Figure 2 illustrates a schematic block diagram of the central control module of an electric vehicle charging system in accordance with a first embodiment of the present invention; Figure 3 illustrates a schematic block diagram of the local charging module of an electric vehicle charging system in accordance with a first embodiment of the present invention; Figure 4 illustrates a schematic diagram of the local charging module of an electric vehicle charging system in accordance with a first embodiment of the present invention; Figure 5 is a schematic diagram of the entire electric vehicle charging system in accordance with embodiments of the present invention; Figure 6 is a flow diagram illustrating the steps involved in the charging process using an electric vehicle charging system in accordance with embodiments of the present invention; Figure 7 is a schematic representation of the cabling requirements for a central control module operating at 16A; Figure 8 is a schematic representation of the cabling requirements for a central control module operating at 32A.; Figure 9 is a schematic perspective view of a cabling infrastructure element intended to provide a dedicated infrastructure for embodiments of the present invention; Figure 10 is a schematic perspective view of a cabling conduit used within a cabling infra-structure element intended to provide a dedicated infrastructure for embodiments of the present invention; and Figure 11 is a schematic view of a cabling infrastructure element intended to provide a dedicated infrastructure for embodiments of the present invention in situ in a footway adjacent a road.

The present invention takes an alternative approach to conventional and prior art EV charging systems. Rather than integrating all of the components of an EV charging system into a single enclosure, or using existing power supplies in lighting columns, the present invention proposes a distributed charging system, where several individual EV chargers connect to a single control cabinet housing metering and communication. EV charging systems of embodiments of the present invention therefore comprise a central module and at least one local charging module, the central control module is adapted to receive electricity from a power distribution network and to distribute electricity to at least one local charging feed, and the least one local charging module, remote from the central control module, and adapted to receive electricity from one of the local charging feeds and to supply electricity to an electric vehicle. The central module comprises at least one central switch, each central switch coupled exclusively to one of the at least one local charging feeds and a central controller in communication with a communications network. Each central switch is adapted to be switched by the central controller on re- ceipt of an authorisation signal transmitted to the central controller via the communica-tions network. Each local charging module comprises a local controller configured to be activated by the switching of a switch coupled to one local charging feed, an outlet adapted to connect to an electric vehicle; and a local switch adapted to be switched by the local controller and coupled to the outlet. This arrangement will now be described in more detail below.

Figure 2 illustrates a schematic block diagram of the central control module of an electric vehicle charging system in accordance with a first embodiment of the present invention. The central control module 1 comprises an enclosure 2 that houses the components required for metering, communications and switching of an outgoing power supply. The central control module 1 is adapted to receive electricity from a power distribu- 1 0 tion network 3 and to distribute electricity to at least one local charging feed 4a-n. An electricity supply 5 from the power distribution network 3 is received into the enclosure 2 via a manual power isolator 6 in the form of an over current protection device, such as a miniature circuit breaker (MCB). This in turn feeds at least one fault detection device 7a-n, typically a 30mA type B residual current breaker (RCD) device with a miniature circuit breaker (MCB) device or a combined residual current breaker with overload protection (RCBO) device, and at least one MID-certified meter 8a-n, each of which is in electrical connection with one of the fault detection devices 7a-n. At least one central switch 9a-n, in the form of a power contactor, is provided to enable at least one local charging feed 4a-n to function. Furthermore, in order to provide earthing to local charging modules the central control module 1 is equipped with a TT earthing spike 10.

The central control module 1 also comprises a central controller 11 in the form of a microcontroller module and a internet enable communications device 12 in communication with a 36/46/5G or other communications network 13. This enables the central controller 11 to send and receive information to and from a remote backoffice 14 that preferably employs the OCPP communications protocol used in electric vehicle charging, however other communications protocols may be used if desired or appropriate. This information includes the authorisation requests and approvals, metering and charging details as required to initiate, maintain and terminate the EV charging process.

Looking at a single local charging feed 4a as an example, the central switch 9a is coupled exclusively to the local charging feed 4a. In addition, the central switch 9a is adapted to be switched by the central controller 11 on receipt of an authorisation signal transmitted to the central controller 11 via the communications network 13. The central switch 9a is coupled to the central controller 11 via an electrical connection 15 to enable this switching, and also coupled to an associated meter 8a, the meter 8a being adapted to record the flow of electricity to the local charging feed 4a. The associated meter 8a is also coupled to the central controller 11 by means clan electrical connection 16 to ena-ble the passing of metering information to the central controller 11 and thus onwards to the OCPP backoffice 14. As described above, on the input side, the associated meter 8a is in electrical connection with a dedicated fault detection device 7a linked to the manual power isolator 6 and the power distribution network 3. On the output side, the local charging feed 4a exits the enclosure of the central control module 1 via an outlet 17. As shown in Figure 2, a plurality of fault detection device-meter-control switch-local charging feed chains are provided within the enclosure 2 of the central control module 1, connected in parallel to each other via the fault detection devices 7a-n. Thus the central control module is coupled to a plurality of local charging feeds 4a-n and adapted to control each central switch 9a-n independently, and wherein each local charging feed 4a-n is coupled to at least one local charging module.

Figure 3 illustrates a schematic block diagram of the local charging module of an electric vehicle charging system in accordance with a first embodiment of the present invention. At least one local charging module 18, remote from the central control module 1, is provided, and adapted to receive electricity from one of the local charging feeds 4a-n and to supply electricity to an electric vehicle 19. The local charging module 18 is mounted on a post 20, and comprises the components required to deliver an electric charge to an electric vehicle 19, housed within an enclosure 21. The local charging module 18 comprises a local controller 22 configured to be activated by the switching of the central switch 8a-n coupled to the local charging feed 4a-n connected to the local charging mod-ule 18, a charging outlet 23 adapted to connect to the electric vehicle 19 and a local switch 24 adapted to be switched by the local controller 22 and coupled to the charging outlet 23. Figure 3 also shows the individual lines within the local charging feed 4a-n and to the electric vehicle 19 in more detail.

Preferably a local charging feed 4a comprises three individual lines: a switch line Li, a neutral line N and a protective earth line PE. It may be preferably to also include a fourth line, a live support line LS, since this will ensure that there is always power to the local controller 22. In the embodiment of the present invention illustrated in the Figures the live support line LS option is included. The charging outlet 23 comprises five individual lines: a switch line L1, a neutral line N, a protective earth line PE, a control pilot line CP and a proximity pilot line PP. The switch line L1 into the local charging module 18 is a live line connected to the local switch 24 and the central switch 9a. The switch line L1 exiting the local charging module 18 via the outlet is also connected to the local switch 24, such that when the local switch 24 is closed the switch line L1 is a live line running directly from the central control module 1 to the charging outlet 23 and consequently the electric vehicle 19. Both the neutral line N and the protective earth line PE run from the central control module 1 to the charging outlet 23. The live support line LS enters the local charging module 18, and rather than connecting directly with the local controller 22 is coupled to a power supply unit 25, which is also coupled to the neutral line N by a line n1 before the local switch 24. The local controller 22 is powered by a connection /1 to the switch line L1 before the local switch 24 and is coupled to the protective earth PE by an earthing connection E. The live support line LS acts as a separate feed to the local controller 22 to ensure that it is always connected to power. However, as described above this may be omitted if desired and the power supply unit 25 connected to the switch line L1 prior to the local switch 24. In this situation the local controller 22 is only connected to power when the central controller 11 has enabled power to the local control module 18 following a successful authentication of a user. A power store, such as a battery, is required to enable the local controller 22 to cease the communication with the electric vehicle 19 once the central controller 11 has opened the central switch 9a. The local controller 22 communicates with the electric vehicle 19 by means of the control pilot line CP and the proximity pilot line PP. Should the electric vehicle 19 wish to terminate the charge or a fault is detected by the local controller 22, such as an open earth connection to the electric vehicle 19, the local switch 24 is opened by a signal from the local controller 22 over the local switch line Is. This is discussed in further detail below.

Figure 4 illustrates a schematic diagram of the local charging module of an electric vehicle charging system in accordance with a first embodiment of the present invention.

The local charging module 18 is mounted within the post 20, although alternatively could be mounted on the outside of the post 20, depending on installation preference. A flexible charging cable 26 is connected to the charging outlet 23 and provided with an outlet connector 27 for attaching to the charging port of the electric vehicle 19. An armoured supply cable 28 houses the local charging feed 4a and is laid within a system duct 29 be-low the surface of the footwayfootway or road 30. An identifier 31 is positioned on the exterior of the post 20 to enable a user of the charging system to identify the local charging module 18. Preferably the identifier 31 is an optical identifier, such as a OR code, bar code, text or numerical string, image or other optically readable device. However, it may be desirable to have an identifier that is readable using an alternative passive or active interrogation signal, for example, RFID tags, NFC or Bluetooth devices.

The electric vehicle charging system in accordance with the embodiment of the present invention outlined above functions in accordance with IEC61851-1 and the signalling protocol outlined therein. This signalling protocol is designed to enable the electric vehicle 19 to control the charging process by following a number of steps and utilising both the control pilot line CP and the proximity pilot line PP coupled to the local control-ler 22. In embodiments of the present invention this signalling protocol is used alongside an authorisation process to determine the identity of the local charging module 18, the identity of a user, and whether or not alternating current (AC) should flow to enable charging to occur. Alternative systems that do not require communication with a vehicle may also be implemented if desired.

Figure 5 is a schematic diagram of the entire electric vehicle charging system in accordance with embodiments of the present invention. This illustrates the central control module 1 linked to a plurality of local charging modules 18, each of which comprises a post 20 and two charging outlets 23, an electric vehicle 19 connected to a local charging module 18, and the communications network 3 and OCPP backoffice function 14. As de- scribed above, an OCPP backoffice 14 is used as part of the authorisation of a user and the process for connection to power for the local control module. However, it may be desirable to use internet enabled devices (loT, Internet of Things) in place of such a backoffice model. For example, the fault detection devices 7a-n may be remote con-trolled MCB devices, with the switches 9a-n replaced with electrical relays comprising a

II

web server and the meters 8a-n replaced with so-called smart meters. Software configured to run remotely on a cloud or other server may communicate with the individual components of the central charging module 1 either directly or via the communication enabled device 12. A central database or library of account details may be held at or ac-cessed by a cloud or other server, enabling the software to run the authorisation process, in conjunction with the app provided on the mobile device, required for a user to access the electric vehicle charging system in accordance with embodiments of the present invention. It may also be desirable for the local controller 22 to be provided as an internetenabled device such that communication may take place between the local controller 22 and the central controller 11 using a communications network in place of a voltage-based signal on the live support line LS. It should be understood that if internet-enabled metering devices are provided these may also communicate metering information directly to the cloud or other server for onward communication to the user. In addition, by providing internet-enabled capability at the local charging module 18 information provided by the electric vehicle during charging can be communicated directly to the cloud or other server for onward sharing with the user.

In order to determine the extent to which internet enabled devices may be used in embodiments of the present invention a prototype model of a central control unit land two local charging modules 18 each having a single charging outlet 23 was built. This de- monstrator also employed the dedicated infrastructure in the form of a cabling infrastruc-ture element described below. Two posts 20 were fabricated from steel tubing but other suitable post materials may be used instead. A central control cabinet 1 was created in a moulded plastic housing and containing a central controller for two internet-enabled electricity sockets placed in housings on the posts 20. In addition to the sockets, light emitting diode (LED) indicator lights were placed in these housings to indicate when the sockets were live. An indicator in the form of a OR code was placed externally on each of the housings. Using software compatible with the controller, a mechanism was created to turn on each socket remotely, independently. Once a socket had been selected, the respective OR code was scanned using an application on a smartphone. This linked via a Will connection to the central controller, which in turn activated the desired socket thus providing a live power source available for use. To indicate that the socket was live, the LED was switched on simultaneously, and remained on for the duration of the live connection to the socket. Any items plugged into the respective socket were able to function normally once power was provided.

Figure 6 is a flow diagram illustrating the steps involved in the charging process us-ing an electric vehicle charging system in accordance with embodiments of the present invention. The method 600 is characterised by the simplicity of the distributed nature of the electric vehicle charging system of embodiments of the present invention. Initially, at step 601, a user identifies the local charging module 18 using the identifier 31. This is done using a mobile device such as a smartphone, for example, taking a photograph of the identifier through an app or webform activated on the mobile device. Alternatively, the app may be stored on the central processing unit of an electric vehicle 19, and an identifier input into this app via an interface in the electric vehicle or utilise geolocation services on the mobile device or in-vehicle. The app or webform also identifies the user, and at step 602 the identity of both the user and the local charging module 18 are sent to the remote OCPP backoffice 14. The remote OCPP backoffice 14 verifies the identity of the user and the local charging module 18 and determines whether the user is able to pay for charging an electric vehicle 19 at step 603. If this is confirmed, the remote OCPP backoffice 14 communicates with the central controller 11 via the communications network 13 and the modem 12 at step 604. This communication is in the form of an authori- 2 0 sation signal received at the central controller 11. Once this authorisation signal has been received at the central controller 11 the user connects the electric vehicle 19 to the charging outlet 23 using the charging cable 26 and the outlet connector 27 provided on the local charging module 18 at step 605. It should be noted however that depending on the user's preferences, the steps 605 and 601 to 604 can be executed in the opposite or- der such that initially the user connects the electric vehicle 19 to the local charging mod-ule 18 followed by the identification of both user and local charging module 18 and the authorisation of the user.

Once the electric vehicle 19 is connected to the local charging module 18 two separate processes occur: the first, between the central controller 11 and the local controller 22 to ensure that electricity from the power distribution network 3 flows from the central control module 1 to the local charging module 18 enabling AC to flow and charge the electric vehicle 19; the second between the local controller 22 and the electric vehicle 19 in accordance with IEC 61851-1. Once the user has been authorised and the central controller 1 has received the authorisation signal, at step 506 the central controller 11 closes the central switch 9a associated with the local charging feed 4a coupled to the identified local charging module 18 and zeros the associated meter 8a. This causes the switch line Li to become live, causing electricity to flow between the central control module 1 and the local control module 18. At step 607 the local controller 22 is activated due to the presence of voltage on the switch line Ll. At step 608 the local controller 22 communi- cates with the electric vehicle 19 and reads the status of the proximity pilot line PP con-nection and determines the integrity of the earth to the electric vehicle. If the status and earth integrity are positive, the local switch 24 is activated causing electricity to flow to the charging outlet 23, ready to initiate charging of the electric vehicle 19. At this point the second process of the local controller 22 communicating with the electric vehicle 19 is initiated.

Once the local controller 22 is activated to communicate with the electric vehicle to determine whether charging can be initiated, it closes the local switch 24 and at step 609 a signal is sent to the electric vehicle 19 to indicate the presence of AC input power available at the charging outlet 23. The electric vehicle 19 detects the presence of the outlet connector 27 and sends a signal to the remote controller 22 on the proximity pilot line PP and connects the proximity pilot line PP and protective earth line PE loop. The proximity pilot line PP may also be known as the proximity pin line or the plug present line, depending on location or electric vehicle 19. Once the outlet connector 27 is detected, control pilot functions can begin by the local controller 22 sending a pulse width modulated (PWM) signal to the electric vehicle 19. At step 610 the local controller 18 sends a 1 kHz PWM square wave signal on the control pilot line CP that is connected to the protected earth line PE on the electric vehicle 19 side. This then enables one of five statuses to be determined: vehicle detected; ready (charging); charging with ventilation; no power or error. This enables the electric vehicle 19 ventilation requirements to be determined and also enables the current capacity of the local charging module 18 to be transmitted to the electric vehicle 19. Finally, at step 611, electricity flows to the electric vehicle 19, which commands the energy flow and charging process. During the charging process the electricity consumption is monitored at the central control module 1 by the associated meter 8a, and regular OCPP meter status messages are sent back to the OCPP backoffice 14 by the central controller 11 via the communications network 13. If the charging rate drops below a minimum threshold the charging process ends and the cen-tral controller 11 deactivates the central switch 9a thus disconnecting the local charging module 18 from the electricity supply.

The processes outlined above therefore enable the following to be determined: whether or not electricity is flowing to the local charging module 8 via the local charging feed 4a; whether or not an electric vehicle 19 is correctly connected to the charging out-let 23; and whether or not the electric vehicle is in a fit state to be charged. During the charging process both the local controller 22 and the electric vehicle 19 monitor the continuity of the protective earth line to the vehicle. Consequently, if a fault is detected, such as an earthing fault, the local controller 22 is able to terminate the charging process by opening the local switch 24. The electric vehicle 19 is informed of a fault by altering the waveform of the PWM signal sent along the control pilot line CP. The local controller 22 will also terminate the charging process by opening the local switch 24 if the maximum or desired level of charge of the electric vehicle 19 has been reached. Usually this is determined by the electric vehicle 19, as this controls the charging demand. Alternatively, it may be desirable for the user to be able to terminate the charging process via the OCPP backoffice 14. In either situation it is necessary for the central controller 11 to open the central switch 9a coupled to the local charging feed 4a serving the identified local charging module 18 in order to cease the flow of electricity between the central control module 1 and the local charging module 18. This effectively terminates the provision of charge to the electric vehicle 19. Opening the central switch 9a also finalises the reading on the associated meter 8a, which is communicated to the OCPP backoffice 14 by the central controller 11 for the purposes of billing. Additionally, during the charging process it may be desirable for the central controller 11 to communicate with the OCPP backoffice 14 to enable status messages or alerts to be sent to the user, for example when charging is about to be terminated or has terminated.

On particular issue overcome by embodiments of the present invention is the cost of cabling such an electric vehicle charging system. Given that it is likely that a number of local charging modules 18 are mounted on posts 20 situated at a distance from the central control module 1 the voltage drop Vdp of the cabling used in the local charging feeds 4a-n running from the central control module 1 to each local charging module 18 must be taken into account. In its simplest form, the voltage drop Vdp of the cabling required to service the local charging module 18 furthest away from or having the greatest cable length required for any one local charging feed 4a-n can be used to determine the cross-sectional area of all of the cabling employed for local charging feeds 4a-n in the system.

However, the cost of cabling with a suitable cross-sectional area for longer cabling re- quirements is relatively high. Take, for example, a local charging module 18 located in a position requiring a cable length for the local charging feed 4a-n of 85m. Based on a typical suitable cable, such as a four-core XLPE/SWA/PVC armoured cable available from City Electrical Factors Limited in the UK, and a voltage drop Vdp acceptable under IEE regula-tions, a cable having a cross-sectional area of 6mm2 is required. If local charging modules 18 are spaced approximately 10m apart at their greatest density then there are eight charging modules 18 requiring cabling, each with two local charging feeds 4a-n. At 2020 prices, the approximate cost of this cabling is around £4248. However, this cost can be reduced as shown in the embodiments below by considering the cabling length and volt- 2 0 age drop Vdp and using cabling having the lowest cross-sectional area meeting these crite-ria.

Figure 7 is a schematic representation of the cabling requirements for a central control module operating at 16A. The central control module 1 supplies the local charging modules 18 with sixteen sets of two local charging feeds 4a-n. In order to determine the required cross-sectional area for each cable used by the local charging feeds 4a-n the following calculation is carried out. Initially, the voltage drop Vdp over the length of cable required for a particular local charging module 18 must be determined. Firstly, for the nth local charging module 18 requiring a cable path length cid from the central control module 1, and a distance (pitch) between each local control module 18 of d, the cable path length do is given by Equation 1: = d (n -71) Equation 1 Once d" is known, the voltage drop Vdp along the cable path length may be determined using Equation 2: Available Voltage = 230 (Vdp d"A) k, 1000) Equation 2 where A is the current that the central control module 1 operates at. Once the voltage drop Vdp is known the value of the appropriate cross-sectional area for the local charging feed 4a-n can be determined from table 4E4B under BS7671:2018. Data in Table 2 was generated using the following values: Parameter Value/units n maximum 8 d 10m A 16A Vdp mV/A/m d, m CS mm2 Table 1: Values and units used in Equations land 2 n d, (m) Voltage drop CS Available per cable length Voltage (V) (mV/A/m) 1 5 19 2.5mm2 228.5 2 15 19 2.5mm2 225.4 3 25 19 2.5mm2 222.4 4 35 19 2.5mm2 219.4 45 12 4mm2 221.4 6 55 12 4mm2 219.4 7 65 7.9 6mm2 221.8 8 75 7.9 6mm2 220.5 Table 2: Cross-sectional area (CS) for local charging feed cabling at 16A and voltage available at a local charging module 18 Comparing the values above and the cabling diagram shown in Figure 6 with using only 6mm2 cable, the total cabling cost also using 2020 prices for this alternative layout is ap-proximately £3286, or a saving of around 33%. Similarly, Figure 7 is a schematic representation of the cabling requirements for a central control module operating at 32A. Repeating the calculations using a value of 32A in place of 16A gives the results shown in Table 3: n claw Voltage drop CS Available per cable length Voltage (mV/A/m 1 5 12 4mm2 228.1 2 15 12 4mm2 224.2 3 25 12 4mm2 220.4 4 35 7.9 6mm2 221.2 45 7.9 6mm2 218.6 6 55 4.7 10mm2 221.7 7 65 4.7 10mm2 220.2 8 75 4.7 10mm2 218.7 Table 3: Cross-sectional area for local charging feed cabling at 32A Again, at 2020 values, cabling the entire system with 10mm2 cabling would be a cost of approximately £6637, whereas using the cabling layout shown in Figure 8 would result in a cost of approximately £5436, or a saving of around 19%. Therefore by choosing cabling appropriately embodiments of the present invention offer a further advantage over existing systems.

In conjunction with improved cabling designs, embodiments of the present invention also provide a dedicated infrastructure system that offers superior cable ducting for electric vehicle charging systems. Such an infrastructure system employs an infrastruc-ture element, which is preferably in the form of a kerb or kerbstone (or "curb", depending on spelling).

Figure 9 is a schematic perspective view of a cabling infrastructure element intended to provide a dedicated infrastructure for embodiments of the present invention.

The electric vehicle charging system of embodiments of the present invention further comprises a cabling infrastructure element 40 adapted to receive a remote charging module 18 and at least one local charging feed 4a. The cabling infrastructure element 40 is substantially "T"-shaped, with the crossbar 41 of the capital T being significantly greater in length than the upright 42 of the capital T. The crossbar 41 of the cabling infrastruc-ture element 40 is preferably solid in cross-section, and formed from a castable material, such as concrete, and may, if desired, comprising a reinforcing means, such as a steel bar or mesh. The cabling infrastructure element 40 is substantially rectangular in cross-section, and has a first, upper surface 43, a second, opposite, lower surface 44, a third external surface 45 positioned between the upper 43 and lower 44 surfaces on the cross-bar 41, and a fourth internal surface 46 covering both the crossbar 41 and the upright 42.

Abutting end pieces 47,48 are provided at each end of the crossbar 41. The upper surface 43 may be imprinted with a tactile and/or visual pattern to indicate the presence of the cabling infrastructure element 40. The upright 42 of the cabling infrastructure element 40 comprises a retainer 49, into which the post 20 of a local charging module 18 is received. The retainer 49 is dimensioned to receive the post 20 and to hold it in a mating fit, where it is secured using a screw arrangement. Alternative means may be used to hold the post 20 in the retainer 49, such as a screw thread, a bayonet fitting, a sprung catch or spring-loaded clip. The upright 42 of the cabling infrastructure element 40 also houses a cabling conduit SO, through which the local charging feed 4a is fed in order to pass through the post 20 to the local charging module 18. Thus, the local charging mod-ule 18 is mounted in, and the local charging feed 4a is housed in, the cabling infrastructure element 40. The cabling conduit 50 is shown in more detail in Figure 10.

Figure 10 is a schematic perspective view of a cabling conduit used within a cabling infrastructure element intended to provide a dedicated infrastructure for embodi-ments of the present invention. In this example, the cabling conduit 50 is illustrated as a hollow metal tube 51, which is cast into the cabling infrastructure element 40. However, it may be desirable to form the cabling conduit 50 from a moulding within the cabling infrastructure element 40. The cabling conduit 50 is substantially tubular in shape, with an opening 52 corresponding to the retainer 49 provided at the uppermost point on the circumference of the tube forming the main body of the cabling conduit 50. This opening 52 is substantially circular, having a radius suitable for receiving the post 20. In this example, the cabling conduit 50 is provided with a screw arrangement 53 for retaining the post securely.

Figure 11 is a schematic view of a cabling infrastructure element intended to pro-vide a dedicated infrastructure for embodiments of the present invention in situ in a footway adjacent a road. The cabling infrastructure element 40 is adapted to fit between a first 54a and second 54b conventional infrastructure element, and slots into a gap 55 provided in a cabling duct 56. The two abutting end pieces 47,48 of the cabling infrastructure element 40 each contact a conventional infrastructure element 54 to enable this flush fit. The cabling infrastructure element 40 is adapted to connect with the cabling duct 56 positioned in a hollows] provided in the footway 58. The hollows] is purpose-built at the edge of a footway 58 adjacent to the conventional infrastructure elements 54. This may be done at the point the footway 58 is constructed or by cutting a section from the footway 58 during installation of the electric vehicle charging system. The cabling duct 56 is adapted to contain the local charging feed 4a en route from the central control module 1. This cabling duct 56 may be buried or obscured with an access cover (not shown). A recess 59 is provided in the footway 58 to accommodate the upright 42 of the "T"-shaped cabling infrastructure element 40 at the point where the cabling infrastructure element 40 connects with the cabling duct 56. Once installed, a post 20 is inserted into the retainer 49 in the cabling infrastructure element 40, such that a local charging module 18 is positioned adjacent the road 60 for access by a user.

By separating the communication, authentication and metering functions into a central control module 1, embodiments of the present invention enable relative freedom in the placing of the local charging modules 18 in an on-street parking situation. Each local charging module 18 is able to benefit from the central TT earth spike 10 provided in the central control module 1, removing the need for local installation of earth spikes or earthing mats. There is also no need to alter existing TN-C-S earthing arrangements provided in street lighting, as with some prior art systems. Preferably, each local charging module 18 is provided with a single-phase electricity supply only, since predominantly overnight charging may be slower than during the daytime when rapid charging is prefer- 1 0 able, thus removing the need for a three-phase electricity supply and the associated switch gear and cabling in the local charging module18 and post 20. One option is to service the central control module 1 with a three-phase supply and split out the individual phases to feed the local charging modules 18.

Each central control cabinet 1 is preferably formed from steel, aluminium or stain- 1 5 less steel, depending on installation location, with the posts 20 in which the local charging modules 18 are located being formed preferably from galvanised steel or aluminium with the enclosure in which the local charging module 18 sits preferably being formed from aluminium sheet or injection moulded plastics materials. A locking mechanism at the local module 18 is not required since this is permanently tethered to the post 20, and a locking mechanism to prevent disconnection during charging is provided on the electric vehicle 19. In addition, since authentication is done via an app on a mobile device or within a vehicle, a user display is not required by the local charging module 18. This reduces the complexity of the microprocessor required for the local controller 22 and removes the need for any form of reader or communications device being installed in the local charging module 18. Reductions in complexity in terms of both components and installation requirements result in a reduced cost for the electric vehicle charging system of the present invention compared with existing systems.

In the above embodiments two charging outlets 23 are provided per post 20. However, depending on the area of installation and individual site requirements, it may be preferable to provide one, three or more charging outlets 23 per post 20. The flexible charging cables 26 tethered to each post preferably have a length of between 2m and 4m and are looped around an appropriate cable management system (not shown). Preferably the outlet connectors 27 are type 2 or type AC charging outlets, suitable for vehicles under both IEC and SAE electric vehicle charging standards. By tethering the charging cables 26 permanently to the post 20 not only is the need bra locking mechanism re-moved, the user has the convenience of a charging cable 26 always being available, without needing to remove a separate cable from the electric vehicle 19 and plug this in at both the local charging module 18 and the electric vehicle itself. Furthermore, should future standards with regard to electric vehicles 19 require tethered cables and type 2 connectors, embodiments of the electric vehicle charging system of the present invention will be able to meet such standards easily.

Claims

CLAIMS1. Electric vehicle charging system comprising: A central control module adapted to receive electricity from a power distribution network and to distribute electricity to at least one local charging feed, comprising: at least one central switch, each central switch coupled exclusively to one of the at least one local charging feeds; and a central controller in communication with a communications network; wherein each central switch is adapted to be switched by the central con-troller on receipt of an authorisation signal transmitted to the central controller via the communications network; And At least one local charging module, remote from the central control module, and adapted to receive electricity from at least one of the local charging feeds and to supply electricity to an electric vehicle, comprising: a local controller configured to be activated by the switching of the central switch coupled to one local charging feed; a charging outlet adapted to connect to an electric vehicle; and a local switch adapted to be switched by the local controller and coupled to the outlet.
2. Electric vehicle charging system as claimed in claim 1, wherein the local charging module is adapted to communicate with the electric vehicle.
3. Electric vehicle charging system as claimed in claim 2, wherein the local charging feed is connected to the local charging module by a switched line Ll, a neutral line N, and a protective earth line PE.
4. Electric vehicle charging system as claimed in claim 2, wherein the local charging feed is connected to the local charging module by a switched line Ll, a neutral line N, a protective earth line PE and a live support line LS.
5. Electric vehicle charging system as claimed in claim 4, wherein the local charging module further comprises a power supply unit coupled to the live support line LS and the neutral line N and adapted to power the local controller.
6. Electric vehicle charging system as claimed in claim 1, wherein the central control module is coupled to a plurality of local charging feeds, and wherein each local charging feed is coupled to at least one local charging module.
7. Electric vehicle charging system as claimed in claim 6, wherein the central control- 1 0 ler is adapted to control each central switch independently.
8. Electric vehicle charging system as claimed in any preceding claim, wherein the central control module further comprises a meter adapted to record the flow of electricity to each local charging feed.
9. Electric vehicle charging system as claimed in any preceding claim, wherein the central controller is adapted to communicate with at least one of a user and an authorisation system for electric vehicle charging.
10. Electric vehicle charging system as claimed in any preceding claim, wherein the local charging module further comprises a second local charging feed and a second charging outlet adapted to connect to an electric vehicle.
11. Electric vehicle charging system as claimed in any preceding claim, wherein the local charging feed comprises cabling having a minimum cross-sectional area as deter-mined by the voltage drop over its length.
12. Electric vehicle charging system as claimed in claim 11, wherein the central control module is coupled to a first local charging feed having a first cross-sectional area and a second local charging feed having a second cross-sectional area, wherein the first cross-sectional area is less than the second cross-sectional area.
13. Electric vehicle charging system as claimed in any preceding claim, wherein the local charging module is mounted in, and the local charging feed is housed in, a cabling infrastructure element.
14. Electric vehicle charging system as claimed in claim 13, wherein the cabling infra-structure element provides a dedicated infrastructure for the electric vehicle charging system.
15. Electric vehicle charging system as claimed in claim 13 or 14, wherein the cabling infrastructure element houses a cabling conduit through which the local charging feed passes.
16. Electric vehicle charging system as claimed in any of claims 13 to 15, wherein the cabling infrastructure element is adapted to fit between a first and a second conventional infrastructure element.
17. Electric vehicle charging system as claimed in any of claims 13 to 16, wherein the cabling infrastructure element is adapted to connect with a cabling duct positioned within a hollow provided in a footway, and wherein the cabling duct is adapted to house at least one local charging feed.