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 for charging two or more electric vehicles.

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 pavement 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, acting as an overcurrent protection device, and a 30mA type B residual cur rent 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 if a TT earth spike is used, 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 un desirable 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 energy 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. Conse quently, 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 neutral connection at any point then effectively the protective earthing is lost and the chassis of the electric vehicle 19 itself may become live, 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 pavement, meaning that charging cables would need to be draped across the pavement to enable on-street charging. Fur thermore, 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, a method of charging at least two electric vehicles at a local charging module adapted to receive electricity from a local charging feed and to supply electricity to at least two elec tric vehicles, comprising: a) identifying the local charging module to an authentication system for electric vehicle charging; b) receiving an authorisation signal in respect of the first vehicle at a central controller in communication with a communications network and housed in a central control module adapted to receive electricity from a power distribu tion network and to distribute electricity to the local charging feed; c) receiving a signal at the local charging module that a first electric vehicle has been connected to a first charg ing outlet provided by the local charging module, the first charging outlet being coupled to the local charging feed by means of a local switching device; d in response to the au thorisation signal, the central controller closing a central switch coupled to the local charging feed to cause electricity to flow between the central control module and the local charging module and closing the local switching device; e) initiating charging of the first electric vehicle; f) repeating steps a) to c) for a second electric vehicle at a second charging outlet provided by the local charging module; g) pausing the charging of the first electric vehicle to wait for a verification signal from the central controller that an authori sation signal has been received; and, the if verification signal is received, h) charging each of the first and second electric vehicle using charging cycles by switching electricity to the first and second charging outlets on and off by switching either the local switching device or the central switch to connect the local charging feed to either the first or the second charging outlet for scheduled time periods to alternate pausing charging and charging until at least one of the first or second electric vehicles has reached a desired electric charge.

By using a cyclical charging method to enable charging of two electric vehicles on a single local charging module significant savings can be made in the cost and complexity of cabling required for the local charging feeds between the central control module and the local control module. It is preferable when providing on street chargers to offer the ca pability of changing two rather than one vehicle with the charger being located equidis- tance between two car parking spaces. This would result in a duplication of supply ca bling in the local charging feed in conventional systems, but the present invention enables a single local charging feed to be used for a local charger that can service two vehicles.

In one embodiment, a charging feed may be connected to each of the first and the second charging outlet, and a central charging switch coupled to each charging feed switches the electricity flow between the first and the second charging outlet.

Preferably, a single charging feed is connected to the first and the second charging outlet, and the local switching device switches the electricity flow between the first and the second charging outlet. The local charging module may further comprise a local con troller coupled to the local switching device and adapted to cause the local switching de vice to switch between the first and the second charging outlets.

If a local controller is used, the method may further comprise the steps of the local controller indicating to the central controller when charging switches between the first and second electric vehicle, and the local controller identifying to the central controller when one of the first and the second electric vehicle ceases charging. In this case. Prefer ably the central controller is coupled to a single energy meter for the local charging feed, and the indicating and identifying steps carried out by the local controller preferably ena ble the central controller to determine the electricity used by each of the first and second electric vehicles.

Preferably, the verification signal is a voltage drop.

The scheduled time periods may be uniform. Alternatively, the scheduled time periods may be non-uniform.

The local charging feed may carry a single-phase electricity supply. Alternatively, the local charging feed may carry a three-phase electricity supply, and the first and the second electric vehicles are charged using different phases of the three-phase electricity supply.

In a second aspect, the present invention also provides an 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 controller on receipt of an authorisation signal transmitted to the central controller via the communications network; and at least one local charging module, re mote 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 switching device configured to be activated by the switching of the central switch coupled to one local charging feed; and at least two charging outlets adapted to connect to an electric vehicle coupled to the local switching device; and a local switch adapted to be switched by the local controller and coupled to the outlet; wherein the local switching device is further adapted to switch the electricity supplied to an electric vehicle between the at least two charging outlets.

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 an 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 an 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 an 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;

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;

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 flow diagram illustrating the steps involved in the charging process of two electric vehicles using an electric vehicle charging system in accordance with embodi ments of the present invention;

Figure 10 is a schematic diagram of the electrical layout and switching system used in embodiments of the present invention to carry out cyclical charging;

Figure 11 is a schematic timing diagram indicating the operation of embodiments of the electric vehicle charging system in accordance with the present invention; and Figure 12 is a schematic diagram of the electrical layout and switching system used in al ternative embodiments of the present invention to carry out cyclical charging.

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 being adapted to receive electricity from a power distribution network and to distribute elec tricity to at least one local charging feed. The at least one local charging module, remote from the central control module, and is 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 receipt of an authorisation signal transmitted to the central controller via the communications network. Each local charging module may comprise a local control ler 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 either by the local controller (if included) or the central 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 an embodiment of the present inven- tion. The central control module 1 comprises an enclosure 2 that houses the components required for energy metering, communications and switching of an outgoing power sup ply. The central control module 1 is adapted to receive electricity from a power distribu 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 la ri, 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 energy meter 8a-n, each of which is in elec trical 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 con trol module 1 may be equipped with either a supply earth, an open-neutral detection de vice, earthing mat orTT earthing spike 10. As well as the central controller 11, the com ponents of the central control module 1 are preferably internet enabled, such that they are adapted to be monitored and/or controlled by the central controller 11 over a net work, such as the internet.

The central control module 1 also comprises a central controller 11 in the form of a microcontroller module and a modem 12 in communication 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 server 14, such as a backoffice 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 in cludes the authentication requests and approvals, energy metering and charging details as required to initiate, maintain, and terminate the EV charging process. The remote server 14 may be a cloud server or other virtual server infrastructure.

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 remote server 14. As described above, on the input side, the associated energy meter 8a is in electrical connection with a dedicated fault de tection device 7a linked to the manual power isolator 6 and the power distribution net work 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 de vice, energy meter-control switch-local charging feed chains are provided within the en closure 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 an embodiment of the present inven tion. This embodiment uses a local controller 22 to control a switching device 24 to ena ble cyclical charging, as described in further detail below. At least one local charging module 18, remote from the central control module 1, is provided, and adapted to re ceive electricity from one of the local charging feeds 4a 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 con figured to be activated by the switching of the central switch 9a coupled to the local charging feed 4a connected to the local charging module 18, a charging outlet 23 adapted to connect to the electric vehicle 19 and a local switching device 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 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, but this is optional. Advantages of having a powered post include that it may be used for ambient night lighting, fault indication to the user (a red light indicating when faulty) and wireless communications (allows communications relay between posts). This also allows the charging to be more easily paused for power management. 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 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 module 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 switching device 24 is closed the switch line LI is a live line running directly from the cen tral 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 mod ule 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 nl before the local switch 24. The local controller 22 is powered by a connection II to the switch line LI be fore the local switch 24 and is coupled to the protective earth PE by an earthing connec tion 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 suc cessful 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 pi lot line CP and the proximity presence line PP. Should the electric vehicle 19 wish to ter- minate 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 an 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 con nector 27 for attaching to the charging port of the electric vehicle 19. An armoured sup ply 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 pavement or road 30. As an alternative, a non-armoured cable may be used in conjunction with an earthed contin uous 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 and charging outlet 23. 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 desira ble to have an identifier that is readable using an alternative passive or active interroga tion 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 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.

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 Remote server function 14.

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 and charging outlet 23 using the identifier 31. This is done using a mobile device such as a smartphone, for example, tak ing 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 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 communications 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 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 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 presence 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 con trol 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 energy meter 8a, and regular OCPP en ergy meter status messages are sent back to the remote server 14 by the central control- ler 11 via the communications network 13. If the charging rate drops below a minimum 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 18 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 remote server 14. In either situation it is necessary for the central controller 11 to open the cen tral 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 energy meter 8a, which is communicated to the remote server 14 by the cen tral 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.

One 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 num ber of local charging modules 18 are mounted on posts 20 situated at a distance from the central control module 1 the voltage drop V _dp 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 V _dp of the cabling re quired 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 sys tem. However, the cost of cabling with a suitable cross-sectional area for longer cabling requirements 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 typi cal 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 V _dp acceptable under IEE regula tions, a cable having a cross-sectional area of 6mm ² 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. Figure 7 is a schematic representation of the cabling requirements for a central control module operating at 16A. The central con trol module 1 supplies the local charging modules 18 with sixteen sets of two local charg ing 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 V _dp over the length of cable required for a particular local charging module 18 must be determined. Firstly, for the n ^th local charging module 18 requiring a cable path length d _n from the central control module 1, and a distance (pitch) between each local control module 18 of d, the cable path length d _n is given by Equation 1:

Equation 1

Once d _n is known, the voltage drop V _d along the cable path length may be determined using Equation 2:

V _dp d _n A\

Available Voltage = 230 — 1000 )

Equation 2 where A is the current that the central control module 1 operates at. Once the voltage drop V _dP 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

Table 1: Values and units used in Equations 1 and 2

Table 2: Cross-sectional area (CSA) 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 6mm ² 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 represen- tation of the cabling requirements for a central control module operating at 32A. Repeat ing the calculations using a value of 32A in place of 16A gives the results shown in Table 3:

Table 3: Cross-sectional area (CSA) for local charging feed cabling at 32A and voltage available at a local charging module 18 Again, at 2020 values, cabling the entire system with 10mm ² 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 exist ing systems. An alternative solution to providing additional cabling to each local charging mod ule 18 to be able to charge two electric vehicles 19 is described below. Embodiments of the present invention offer the ability to be able to utilise a single local charging feed 4a in conjunction with two charging outlets 23a, 23b at a single local charging module 18. One scenario for charging two electric vehicles 19a, 19b, is as follows. Initially, a first electric vehicle 19a connects to the local charging module using the first charging outlet 23a and following the receipt of an authorisation signal at the central controller, charging of the electric vehicle 19a is initiated. Subsequently, during charging of the first electric vehicle 19a, a second electric vehicle 19b connects to the second charging outlet 23b in order to begin charging. Consequently, a method of charging both electric vehicles 19a, 19b from the same local charging feed 4a-n is required.

Figure 9 is a flow diagram illustrating the steps involved in the charging process of two electric vehicles using an electric vehicle charging system in accordance with embod- iments of the present invention. This outlines the steps used in a cyclical charging meth od in accordance with the present invention. At step 901 a local charging module is iden tified to an authentication system for electric vehicle 19 charging. This is by means of a barcode or other identifier, as above. At step 902, an authorisation signal in respect of the first electric vehicle 19a is received at the central controller 11, which is in communi cation with a communications network 13 and housed in a central control module 1 adapted to receive electricity from a power distribution network 3 and to distribute elec tricity to the local charging feed 4 a -n. At step 903, the local charging module 18 receives a signal that a first electric vehicle 19 has been connected to a first charging outlet 23a provided by the local charging module 18. The first charging outlet 23a is coupled to the local charging feed 4a by a local switching device 24a. In response to the authorisation signal, at step 904 a central switch 9a coupled to the local charging feed 4a-n is closed by the central controller 11 causing electricity to flow between the central control module and the local charging module, and at step 905, charging of the first electric vehicle 19a is initiated.

Subsequent to this point, and whilst the first electric vehicle 19a is charging, a sec ond electrical vehicle 19b also requires charging. At step 906, steps 901 to 903 are re peated for the second electric vehicle 19b. Before any charging can begin, the second vehicle 19b and user must undergo the same authentication process as the first vehicle 19a. For this to happen, at step 907 the charging of the first electric vehicle 19a is paused to wait for a verification signal from the central controller 11 that an authorisation signal has been received, such that at step 908 if the verification signal has been received, the first 19a and second 19b electric vehicles are charged using charging cycles by switching electricity to the first 23a and second 23b charging outlets on and off for scheduled time periods to alternate pausing charging and charging until at least one of the first 19a or second 19b electric vehicles has reached a desired electric charge. This is done by switch ing either the local switching device 24a or the central switch 9a to connect the local charging feed to either the first or the second charging outlet.

Figure 10 is a schematic diagram of the electrical layout and switching system used in embodiments of the present invention to carry out cyclical charging. The central con trol module 1 is connected to three local charging modules 18a, 18b, 18c located at vari- ous distances away from the central control module 1 by means of three local charging feeds 4a, 4b, 4c. The central control module 1 is provided with three central switches 9a, 9b, 9c, each connected to a respective energy meter 8a, 8b, 8c to monitor the amount of electricity supplied to each local charging module 18a, 18b, 18c via the local charging feeds 4a, 4b, 4c. Within each local charging module 18a, 18b, 18c a local switching device 24a, 24b, 24c is coupled to the respective incoming local charging feed 4a, 4b, 4c, and controlled by a respective local controller 22a, 22b, 22c. Each local charging module 18a, 18b, 18c is provided with a first charging outlet 23a and a second charging outlet 23b, to enable the connection of two electric vehicles 19a, 19b to each local charging module 18a, 18b, 18c simultaneously. In the embodiment illustrated, a single charging feed 4a, 4b, 4c is connected between the central control module 1 and the local charging module 18. In order to be able to charge two electric vehicles simultaneously, the switching de vice 24a, 24b, 24c connects the local charging feed 4a, 4b, 4c to each of the firsts 23a and second 23b charging outlets alternately, creating a cyclical charge. Each switch connect 32a, 32b of the local switching device 24a is associated with one of the first 23a and sec ond 23b charging outlets respectively.

The effect of such cyclical charging is illustrated in Figure 11 using the embodi ment illustrated in Figure 10. Figure 11 is a schematic timing diagram indicating the oper ation of embodiments of the electric vehicle charging system in accordance with the pre sent invention. Time is indicated in general by the horizontal axis. A single local charging module 18a illustrated in Figure 10 is used to describe the process for simplicity, but the technique is replicated for each local charging module 18b, 18c coupled to the central control module 1. Lines A to F indicate the following:

A: time for which the first electric vehicle 19a is parked;

B: time for which the second electric vehicle 19b is parked;

C: voltage applied to the local charging module 18;

D: power at the first charging outlet 23a;

E: power at the second charging outlet 23b;

F: total power flow at the energy meter 8a.

The timing runs as follows: 1. The first electric vehicle 19a parks at the local charging module. The authentica tion process is carried out (steps 901 to 903 above). The first electric vehicle 19a is con nected to the first charging outlet 23a, which is noted by the local controller 18a, and waits for charging to begin.

2. Voltage is applied to the local charging module 18 (step 904). This is done by the central switch 9a being closed such that the local charging feed 4a is live.

3. Power is supplied to the first charging outlet 23a, and charging is initiated for the first electric vehicle 19a (step 905 by the local controller 22a causing the local switching device 24a to close by connecting to the switch contact 32a coupled to the first charging outlet 23a.

4. The total energy flow at the energy meter 8a in the central control module 1 be gins to register.

5. The second electric vehicle 19b parks at the local charging module. The authenti cation process is carried out (step 906) for this second electric vehicle 19b, which is con nected to the second charging outlet 23b.

6. There is a pause in the charging of the first electric vehicle 19a whilst the local controller 22a waits for verification from the central controller 11 that the second electric vehicle 19b is authorised for charging. This ceases power at the first charging outlet 23a and power flow at the energy meter 8a as the switch contact 32a at the first charging out let 23a is opened by the local controller 22a.

7. The verification is received from the central controller 11 via a drop in voltage on the local charging feed 4a to the local charging module 18a (step 907). Charging of the second electric vehicle 19b is initiated (step 908) by the local controller 22a closing the switching device 24a by connecting to the switch contact 32b coupled to the second charging outlet 23b.

8. The two electric vehicles 19a, 19b undergo cyclical electric charging. This is done by switching electricity to the first 23a and second 23b charging outlets on and off for scheduled time periods to alternate pausing charging and charging (step 908). The local switching device 24a is switched by the local controller 22a to connect the local charging feed 4a to either the first 23a or the second 23b charging outlet for scheduled time peri ods to alternate pausing charging and charging. This is done in the same manner as the original connection, by the local controller 22a causing the local switching device 24a to close the switch contact 32a at the first 23a and open the switch contact 32b at the sec ond 23b charging outlets, and vice versa, alternately.

9. The first electric vehicle 19a reaches the desired level of charge and charging via the first charging outlet 23a ceases. The local controller 22a ceases to make any connec tion between the local charging feed 4a and the first charging outlet 23a, by opening the associated switch contact 32a and the first electric vehicle 19a disconnects from the local charging module 18. As indicated in Figure 10, this may cut short one of the power cycles to accommodate the disconnection of the first electric vehicle 19a. The local controller 22a then feeds back the information regarding the disconnection of the first electric vehi cle 19a and the portion of the total connection time in which the local charging feed 4a is live for which the first electric vehicle 19a was connected to the local charging feed 4a and charging to the central controller 11.

10. The second electric vehicle 19b continues to charge until the desired level of charge is reached, at which point charging via the second charging outlet 23b ceases by the local controller opening the associated switch contact 32b and the second electric vehicle 19b disconnects from the local charging module 18. The local controller 22a then feeds back the information regarding the disconnection of the second electric vehicle 19b and the portion of the total connection time in which the local charging feed 4a is live for which the second electric vehicle 19b was connected to the local charging feed 4a and charging to the central controller 11. In order for the central control module 1 to be able to send the correct billing data back to the remote server 14 it is necessary for the local charging module to be able to indicate at which point the first electric vehicle 19a is being charged and at which point the second electric vehicle 19b is being charged. One manner in which this may be achieved is at the point that the first electric vehicle 19a ceases charging. At this point the first electric vehicle 19a ceases communication with the local controller 22. Given that the local controller 22 knows that the first electric vehicle 19a was connected to the first charging outlet 23a it is able to signal to the central controller 11 that charging has ceased via this charging outlet 23a. The local controller 18 is also able to indicate to the central controller 11 when charging switches between the first electric vehicle 19a and the second electric vehicle 19b due to the temporary drop in power flow at the energy meter 8a indicated in Figure 10. Since the central controller 11 is coupled to a single energy meter 8a for the local charging feed 4a, the indicating and identifying steps carried out by the local controller enable the central controller to de termine the electricity used by each of the first and second electric vehicles. Given that charging is cyclical the central controller 11 is able to work out how many cycles were attributed to the first electric vehicle 19a and therefore inform the remote server 14 the correct energy metering information for billing.

Figure 12 is a schematic diagram of the electrical layout and switching system used in alternative embodiments of the present invention to carry out cyclical charging. In contrast to the embodiment illustrated in Figure 10, rather than employing a local con troller 22 in the local charging module 18, or a switching device 24 that connects directly to contacts associated with a first 23a and second 23b charging outlet within the local charging module 18, the central controller 11 controls the switching of the local charging feed 4a between the first 23a and the second 23b charging outlet. In this embodiment, the central control module 1 is also connected to three local charging modules 18a, 18b, 18c but by means of two local charging feeds 4ai, 4aii, 4bi, 4bii, 4ci, 4cii per local charging module 18a, 18b, 18c. Each of the two local charging feeds 4ai, 4aii, 4bi, 4bii, 4ci, 4cii is connected to a local switching device 24ai, 24aii, 24bi, 24bii, 24ci, 24cii, which in turn is connected to a charging outlet 23a, 23b. Taking a single local charging module 18a as an example, for simplicity, local charging feeds 4ai, 4aii are coupled exclusively to the first charging outlet 23a and the second charging outlet 23b, respectively, by means of the local switching devices 24ai, 24aii. In the central control module 1 each of the local charg ing feeds 4ai, 4aii, 4bi, 4bii, 4ci, 4cii is coupled to a central switch 9ai, 9aii, 9bi, 9bii, 9ci,

9cii via an energy meter 8ai, 8aii, 8bi, 8bii, 8ci, 8cii, such that each energy meter 8ai, 8aii, 8bi, 8bii, 8ci, 8cii gathers dedicated energy metering information for the charging outlet 23a, 23b it is connected to. A single local charging module 18a illustrated in Figure 12 is used to describe the process for simplicity, but the technique is replicated for each local charging module 18b, 18c coupled to the central control module 1. Turning again to Fig ure 10, the timing for the cyclical charging in the embodiment of Figure 12 is as follows:

1. The first electric vehicle 19a parks at the local charging module. The authentica tion process is carried out (steps 901 to 903 above). The first electric vehicle 19a is con- nected to the first charging outlet 23a, which is noted by the central controller 11, and waits for charging to begin.

2. Voltage is applied to the local charging module 18 (step 904). This is done by the central switch 9a being closed such that the local charging feed 4ai connected to the first charging outlet 23a is live.

3. Power is supplied to the first charging outlet 23a, and charging is initiated for the first electric vehicle 19a (step 905), by the central controller 11 causing the local switching device 24a to close by connecting to the swich contact 32ai coupled to the first charging outlet 23a.

4. The total energy flow at the energy meter 8a in the central control module 1 be gins to register.

5. The second electric vehicle 19b parks at the local charging module. The authenti cation process is carried out (step 906) for this second electric vehicle 19b, which is con nected to the second charging outlet 23b.

6. There is a pause in the charging of the first electric vehicle 19a whilst the central controller 11 verifies that the second electric vehicle 19b is authorised for charging. This ceases power at the first charging outlet 23a as the central controller 11 closes the switch 9ai and power flow at the energy meter 8ai as the switch contact 32ai at the first charging outlet 23a is opened by the central controller 11.

7. The verification is received from the central controller 11 via a drop in voltage on the local charging feed 4a to the local charging module 8 (step 907). Charging of the sec ond electric vehicle 19b is initiated (step 908) by the central controller 11 closing the switching device 24b by connecting to the switch contact 32bi coupled to the second charging outlet 23b. This is done by the central controller 11 closing the central switch 8aii, causing the local charging feed 4aii to be live.

8. The two electric vehicles 19a, 19b undergo cyclical electric charging. This is done by switching electricity to the first 23a and second 23b charging outlets on and off for scheduled time periods to alternate pausing charging and charging (step 908). This is achieved by switching the central switches 8ai, 8aii to connect to their respective local charging feed 4ai, 4aii such that either the first 23a or the second 23b charging outlet re ceives electricity for scheduled time periods to alternate pausing charging and charging. This is done in the same manner as the original connection, by the central controller 11 causing the local switching device 24a to close the switch contact 32ai at the first 23a and open the switch contact 32bi at the second 23b charging outlets, and vice versa, alter nately.

9. The first electric vehicle 19a reaches the desired level of charge and charging via the first charging outlet 23a ceases. The central controller 11 opens both the central switch 9ai and the local switching device 24a, such that any connection between the local charging feed 4ai and the first charging outlet 23a is ceased. The first electric vehicle 19a disconnects from the local charging module 18a. As indicated in Figure 10, this may cut short one of the power cycles to accommodate the disconnection of the first electric ve hicle 19a. The central controller 11 becomes aware that the charging of the first electric vehicle 19a is terminated at the point that either the first electric vehicle 19a is discon nected from the first charging outlet 23a, or the point that the battery in the first electric vehicle 19a reaches either a maximum or desired charge level. This is communicated by the first electric vehicle 19a to the central controller 11.

10. The second electric vehicle 19b continues to charge until the desired level of charge is reached, at which point charging via the second charging outlet 23b ceases and the second electric vehicle 19b disconnects from the local charging module 18a. The cen tral controller 11 becomes aware that the charging of the second electric vehicle 19b is terminated at the point that either the second electric vehicle 19b is disconnected from the second charging outlet 23b, or the point that the battery in the second electric vehicle 19b reaches either a maximum or desired charge level. This is communicated by the sec ond electric vehicle 19b to the central controller

11. Generally, in Europe, there are two AC charging rates: 16A (3.7kW)and 32A (7.4kW) as in the examples above. Whilst all electric vehicles 19 can charge at the 3.7kW rate, some are unable to use the 7.4kW rate currently. To charge at the higher 7.4kW rate a user may need to purchase an optional improved charging module built into the electric vehicle 19 during manufacture. It may be desirable therefore to ensure that the cabling used in the local charging feed 4a and the components within the central control module 1 and the local control module 18 to be able to supply the 7.4kW charge rate (by using a 32A central control module 1) as long as electric vehicles 19 connecting to the local supply module 18 are able to take this higher charge rate. If two mismatched elec tric vehicles 19 are charging together, for example, one with a 3.7kW capability (limited by its onboard charger) and one with a 7.4kW capability it may be desirable to enable the local control module 18 to charge the electric vehicle 19 accepting the 3.7kW rate for twice as long per cycle as the electric vehicle 19 accepting the 7.4kW rate. This results in the same energy flow to both electric vehicles 19. Consequently, depending on the set up of the central control module 18 and the local charging module 18 the scheduled time periods in the charging cycle may be uniform or non-uniform.

In the example shown in Figure 12 it is also possible to charge two electric vehicles 19 simultaneously. Whilst the example above describes cyclical charging, since there is a separate local charging feed 4ai, 4aii dedicated to each charging outlet 23a, 23b these charging outlets 23a, 23b may be live simultaneously.

In the examples pertaining to Figures 8 to 12 above the assumption is that charg ing is being done using a single-phase electricity supply rather than a three-phase electric ity supply. However, it is also possible to utilise a three-phase electricity supply when charging two electric vehicles 19 from the same local charging module 18, since a single phase per vehicle can be split out from the supply, such that the electric vehicles 19 are charge using different phases of the three-phase supply.

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 or oth er earthing device, such as an earthing mat or open neutral detector provided in the cen tral control module 1, removing the need for local installation of earth spikes, open neu tral detectors 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, for example, by providing an additional earthing rod. Preferably, each local charging module 18 is provid ed with a single-phase electricity 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 module 18 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 galva nised 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. If tethered cables are 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 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 micro processor required for the local controller 22 and removes the need for any form of read er 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 re duced 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. When teth ered flexible charging cables 26 are used, these 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. Alternatively, the charging outlets may be type 1 charging outlets