WO2022023563A1

WO2022023563A1 - Electric vehicle charging system

Info

Publication number: WO2022023563A1
Application number: PCT/EP2021/071483
Authority: WO
Inventors: Paul Weston; Simon White
Original assignee: Siemens Mobility Limited
Priority date: 2020-07-31
Filing date: 2021-07-30
Publication date: 2022-02-03
Also published as: GB2597740A; GB202011980D0; GB2603739A

Abstract

An electric vehicle charging system and method of charging an electric vehicle are disclosed. The electric vehicle charging system is formed of a distributed system comprising a central control module housing communications, user authentication and energy metering devices and a local charging module housing at least one outlet connector for connecting to an electric vehicle.

Description

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 ve hicles 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 access ing 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. Authentication 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 Identi fication 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 an energy meter 109 that records the elec tricity usage during charging, the energy 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, cou pled to the outlet connector 111 and also under the control of the microcontroller mod ule 101 to prevent unauthorised disconnection and disconnection during charging. If dis connection 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 energy meter 109 is coupled to a power distribution network 112 via a power inlet 113 (either single- or three-phase), a manual isolator 114 and a 30mA type B residual current breaker (RCD) 115. Each EV charger is provided with a TT earth spike, earthing mat or open neutral detector (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 NFC com munications 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 or an open neutral detector 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 energy meter ing are not required, and consequently are lower in cost than publicly available EV chargers. Energy metering (for example, via the electricity meter already installed in a property), security and installation are the responsibility of the homeowner, but this re quires adequate land adjacent a property to park a vehicle during charging. Consequent ly, this is not suitable for on-street parking locations.

One solution to this issue that has been proposed previously is to use street light 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 leak age 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 col umn, and their EV charging provide bills them appropriately for electricity used. Such systems are provided by Ubitricity™ (https://www.ubitricity.com/en/) and Char.gy™ (https://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 the TT earthing system required by EV chargers, and as such this also requires modification. For example, if a TN-C-S system is used and there is a loss of the protective earth and neutral (PEN) at any point the electric vehicle 19 itself be comes the return path for any current, risking electric shock if the electric vehicle 19 is touched. Therefore, a common approach is to provide an earthing rod in order to satisfy standards such as BS7671:2018. 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 from a remote backoffice; 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.

The present invention offers the advantages that the energy metering and authen tication 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 hard ware required to contain energy 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 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 switch is further adapted to control the supply of electricity to the charging outlet to supply the electric vehicle.

The central control module is preferably coupled to a plurality of local charging feeds, and wherein each local charging feed is coupled to at least one local charging mod ule.

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

The central control module preferably further comprises an energy meter adapted to record the flow of electricity to each local charging feed. The central controller may be adapted to communicate with at least one of a user and an authentication system for electric vehicle charging.

The local charging module may further comprise a second local charging feed and a second charging outlet adapted to connect to an electric vehicle.

The local charging module may further comprise a second charging outlet adapted to connect to a second electric vehicle such that the local charging module is adapted to supply electricity to two electric vehicles simultaneously.

The local charging module may further comprise a second charging outlet adapted to connect to an electric vehicle, and the local switch is adapted to switch between the first charging outlet and the second charging outlet.

The system preferably comprises a plurality of local charging modules, each re mote from the central control module, and each adapted to receive electricity from one of a plurality of respective local charging feeds and to supply electricity to a plurality of electric vehicles simultaneously.

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 accord ance with embodiments of the present invention; and

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 inven tion.

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 energy metering and communica tion. 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 elec tricity 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 com prises 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 communi cations network. 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 commu nications network from a remote backoffice. 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 arrange ment 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 com ponents required for energy metering, communications and switching of an outgoing power supply. The central control module 1 is adapted to receive electricity from a pow er distribution 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 de vice, such as a miniature circuit breaker (MCB). This in turn feeds at least one fault detec tion 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 over load protection (RCBO) device, and at least one MID-certified energy 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 Depending on the nature of the electricity supply, the central control module 1 may be equipped with a supply earth, an open-neutral detection device, and earthing mat or a TT earthing spike 10.

The central control module 1 also comprises a central controller 11 in the form of a microcontroller module and an internet enable communications device 12 in communi cation with a 3G/4G/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. The remote back office 14 may be a remote server, a cloud server or other virtual server infra structure. This information includes the authentication requests and approvals, energy 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 energy meter 8a, the energy meter 8a being adapted to record the flow of electricity to the local charging feed 4a. The associ ated energy meter 8a is also coupled to the central controller 11 by means of an electrical connection 16 to enable the passing of energy metering information to the central con troller 11 and thus onwards to the backoffice 14. As described above, on the input side, the associated energy 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 energy 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 detec tion devices 7a-n. Thus, the central control module is coupled to a plurality of local charg- ing feeds 4a -n and adapted to control each central switch 9a-n independently, and where in 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 mount ed 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 com prises 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. The local charging module 18 is also adapted to communicate with the electric vehicle 19 by means of the local controller 22. Figure 3 also shows the individual lines within the local charging feed 4a-n and to the electric vehicle 19 in more detail.

In the case of a single-phase feed, preferably a local charging feed 4a comprises three individual lines: a switch line LI, a neutral line N and a protective earth line PE, alt hough alternatives may be available. 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, but this is optional. In the embodiment of the present invention illustrated in the Fig ures the live support line LS option is included. The charging outlet 23 comprises five in dividual lines: a switch line LI, a neutral line N, a protective earth line PE, a control pilot line CP and a proximity presence line PP. The switch line LI into the local charging mod ule 18 is a live line connected to the local switch 24 and the central switch 9a. The switch line LI 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 LI is a live line run ning directly from the central control module 1 to the charging outlet 23 and consequent ly 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. If include, 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 neu tral line N by a line nl before the local switch 24. The local controller 22 is powered by a connection II to the switch line LI before the local switch 24 and is coupled to the protec tive 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 LI 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, capacitor or similar device 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 presence line PP. Should the elec tric 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. 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 flexi ble 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. The outlet 23 may be a tethered cable, terminated in a plug adapted to mate with a specific vehicle inlet, or optionally may be a socket outlet fixed to the local charging module 18. An ar moured supply cable 28, such as an SWA (steel wire armoured) cable houses the local charging feed 4a and is laid within a system duct 29 below the surface of the footway or road 30. As an alternative, a non-armoured cable may be used in conjunction with an earthed continuous metallic duct. 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 QR 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 embodiments of the present invention comprises a plurality of local charging modules, remote from the central control module. All of these are adapted to receive electricity from a plurality of respective local charging feeds and to supply elec tricity to a plurality of electric vehicles simultaneously.

The electric vehicle charging system in accordance with the embodiment of the present invention outlined above functions in accordance with IEC61851-1 and the signal ling 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 presence line PP coupled to the local con troller 22. In embodiments of the present invention this signalling protocol is used along side an authentication 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 ac cordance 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 backoffice function 14. As described above, a backoffice 14 is used as part of the authentication 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 la-n may be remote controlled MCB devices, with the switches 9a-n replaced with electrical relays comprising a web server and the energy 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 cen tral charging module 1 either directly or via the communication enabled device 12. A cen tral database or library of account details may be held at or accessed by a cloud or other server, enabling the software to run the authentication 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 internet-enabled device such that communication may take place between the local controller 22 and the central con troller 11 using a communications network in place of a voltage-based signal on the live support line Z.S. It should be understood that if internet-enabled energy metering devices are provided these may also communicate energy 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. The local charging module further comprises a second charging outlet adapted to connect to a second electric vehicle such that the local charg ing module is adapted to supply electricity to two electric vehicles simultaneously . Since the central control module 1 is able to support a plurality of independent local charging modules, a plurality of electric vehicles 19 can be charged simultaneously. The number of local charging modules 18 is only limited by infrastructure considerations, such as the size of the cabinet, the streetscape selected for installation and the local electricity grid capa bility.

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, scanning 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 server 14. The remote server 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, for example, the user has sufficient funds or credit. If this is confirmed, the remote server 14 communicates with the central controller 11 via the communica tions network 13 and the modem 12 at step 604. This communication is in the form of an authorisation 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 order such that initially the user connects the electric vehicle 19 to the local charging module 18 followed by the identification of both user and local charging module 18 and the authentication of the user.

Once the electric vehicle 19 is connected to the local charging module 18 two sep arate 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 con troller 1 has received the authorisation signal, at step 606 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 energy 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 LI. At step 608 the local controller 22 communicates with the electric vehicle 19 and reads the status of the proximity presence line PP connection 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 pres ence line PP and connects the proximity presencepresence line PP and protective earth line PE loop. 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 detect ed; ready (charging); charging with ventilation; no power or error. This enables the elec tric 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. Fi nally, 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 energy meter 8a, and regular OCPP energy meter status messages are sent back to the backoffice 14 by the central con troller 11 via the communications network 13. If the charging rate drops below a mini mum threshold the charging process ends and the central 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 con tinuity 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 de termined 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 to the electric vehicle 19. Opening the central switch 9a also finalises the reading on the associ ated energy meter 8a, which is communicated to the remote server 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 remote server 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.

By separating the communication, authentication and energy 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, earthing mat or open neutral detector provided in the central control module 1, re moving the need for local installation of earthing devices. 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 elec tricity supply only, since predominantly overnight charging may be slower than during the daytime when rapid charging is preferable, thus removing the need for a three-phase electricity supply and the associated switch gear and cabling in the local charging mod- ulel8 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 module 1 is preferably a cabinet formed from galvanised steel, aluminium or stainless 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 prefera bly being formed from aluminium sheet or injection moulded plastics materials. Where a tethered cable is used, 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 discon- nection during charging is provided on the electric vehicle 19. In addition, since authenti cation is done via an app on a mobile device or within a vehicle, a user display is not re quired by the local charging module 18. This reduces the complexity of the microproces sor 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 exist ing systems.

In the above embodiments two charging outlets 23 are provided per post 20 and therefore local charging module 18. 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. If the flexible charging cables 26 are tethered to each post prefer ably 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. Furthermore, should future standards with regard to electric vehicles 19 re quire tethered cables and type 2 connectors, embodiments of the electric vehicle charg ing system of the present invention will be able to meet such standards easily. However, a type 1 outlet connector may be used instead. More than one local charging feed 4a may be provided for each local charging module 18, with each local charging feed 4a be ing connected exclusively to a single charging outlet 23. Alternatively, the local switch is adapted to switch between the first charging out-let and the second charging outlet. This provides independent and simultaneous charging of two electric vehicles 19 at the same local charging module 18.

Claims

1. 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 from a remote backoffice; 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 switch is further adapted to control the supply of electricity to the charging outlet to supply the electric vehicle.

3. Electric vehicle charging system as claimed in claim 1 or 2, wherein the local charg ing module is adapted to communicate with the electric vehicle.

4. Electric vehicle charging system as claimed in claim 3, wherein 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.

5. 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.

6. Electric vehicle charging system as claimed in claim 5, wherein the central control ler is adapted to control each central switch independently.

7. Electric vehicle charging system as claimed in any preceding claim, wherein the central control module further comprises an energy meter adapted to record the flow of electricity to each local charging feed.

8. 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 authenti cation system for electric vehicle charging.

9. 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 charg ing outlet adapted to connect to an electric vehicle.

10. Electric vehicle charging system as claimed in any preceding claim, wherein the local charging module further comprises a second charging outlet adapted to connect to an electric vehicle, and the local switch is adapted to switch between the first charging outlet and the second charging outlet.

11. Electric vehicle charging system as claimed in any preceding claim, wherein the local charging module further comprises a second charging outlet adapted to connect to a second electric vehicle such that the local charging module is adapted to supply electricity to two electric vehicles simultaneously.

12. Electric vehicle charging system as claimed in claim 1, further comprising a plurali ty of local charging modules, each remote from the central control module, and each adapted to receive electricity from one of a plurality of respective local charging feeds and to supply electricity to a plurality of electric vehicles simultaneously.