GB2489988A

GB2489988A - Improvements in electrical connections

Info

Publication number: GB2489988A
Application number: GB1106401.1A
Authority: GB
Inventors: Martin Banks
Original assignee: Nissan Motor Manufacturing UK Ltd
Current assignee: Nissan Motor Manufacturing UK Ltd
Priority date: 2011-04-15
Filing date: 2011-04-15
Publication date: 2012-10-17
Anticipated expiration: 2031-04-15
Also published as: WO2012139778A4; WO2012139778A2; GB2489988B; WO2012139778A3; GB201106401D0

Abstract

The present invention relates to the charging of electric vehicles and particularly to improvements in the electrical connection or coupling, for example, an electrical plug and / or socket between the charging point and the vehicle. A device is provided for mounting in an electrical connection between an electrical power supply and an electrical load such as a power storage means, the device 410 comprising a temperature sensing means 412U and a communication means 414, means 412 being mounted near to at least one electrical conductor, means 414 being arranged to communicate temperature data from sensing means 412 to at least one of said electrical power supply and/or load. In a charging system that uses an EVSE (Electrical Vehicle Safety Equipment) unit (6, Fig. 4), the temperature sensing means may modify the signal on the pilot line (3cp, Fig. 3) to communicate temperature data and/or to control vehicle charging, for example to stop charging by signalling a fault if theconnection is over temperature. Further temperature sensors may be provided to facilitate measurement of surfaces which a user may handle in use. The device (10, Fig 5a) may be arranged for use with a typical mains plug (90, fig 6a).

Description

IMPROVEMENTS IN ELECTRICAL CONNECTIONS

Field of the invention

The present invention relates to the charging and re-charging of electric vehicles and particularly, but not exclusively, to improvements in the electrical connection or coupling, for example an electrical plug and/or socket, between the charging point and the vehicle being charged. Aspects of the invention relate to a device, to an electrical connection, to a vehicle charging system, and to a method of charging an electric vehicle.

Background of the invention

Electrically powered domestic or commercial vehicles, such as automobiles, are becoming increasingly common. Most forms of electric vehicle (EV) or hybrid electric vehicle (HEV) are provided with an energy storage device, such as a battery, that supplies electric power to one or more motors for providing motive power to the vehicle. In some cases, the vehicle is provided with an electrical connection, such as a socket, to permit recharging of the battery by connection to a suitable external power supply, for example a domestic mains voltage consumer unit.

Such vehicles are commonly referred to as plug-in hybrid' or "plug-in electric" vehicles. The user of either a plug-in hybrid vehicle or an EV is required to electrically connect their vehicle to a dedicated charging station or a domestic power supply on a regular basis in order to recharge the vehicle after use.

The electrical infrastructure needed to electrically recharge such vehicles is still being developed in many countries where transport systems have, until recently, developed around the needs of vehicles powered by internal combustion engines.

Some countries have started to provide dedicated recharging stations, able to supply the relatively high electrical current necessary to facilitate a rapid recharge of an electrically powered vehicle. However, the availability of these recharging stations will be limited, at least initially, until electrically powered vehicles become more popular and developing national electrical infrastructures have time to catch up with demand. Until such time as these dedicated vehicle recharging stations are commonplace, many early adopters of electrically powered vehicles will rely on recharging their vehicle via a domestic electrical outlet.

A known problem with using a domestic electrical outlet to recharge an electrically powered vehicle is the limited current capacity available to the vehicle. Typically a dedicated vehicle recharging station may provide up to 400V at around 60A, whereas a typical domestic electrical outlet may be limited to 220V at 13A or even less. Clearly, the rate of charge -and thus the time taken to recharge an electrically powered vehicle -will be proportionally slower using a domestic electrical outlet, compared to using a dedicated vehicle recharging station. The infrastructure behind most domestic electrical outlets was never intended to supply such a high capacity electrical consumer as an electrically powered vehicle. As such, there are several challenges which the electricity providers and vehicle manufacturers alike must work to address.

A problem may arise if electrically powered vehicles become more commonplace, as there may be a significant increase in demand for recharging such vehicles at home. In this case, the vehicle may be parked in a domestic garage or carport or alternatively parked outside, for example on a private driveway. Typically, the most conveniently positioned domestic electrical outlet will be relatively distant from the main electrical supply to the residence. In this case, the distance from, for example, a fuse box or electrical meter tends to entail a relatively long electrical spur, resulting in electrical losses in the wiring between the residential supply and the outlet. Such losses affect the available rate of charge for the electrically powered vehicle, increasing recharge times. Due to the longer recharge times, the user is likely to leave the vehicle unattended for extended periods of time during the recharging cycle. However, if the user attempts to disconnect the vehicle from the domestic electrical outlet during, or shortly after recharging is completed, it is possible that the electrical plug and associated electrical outlet may have become warm, or even hot, to the touch due to the relatively high current drawn by the vehicle. This may lead to a perception that the recharging system is unsafe or that the electrical equipment in use is defective.

To minimise heating of the plug, it is possible to use thermal insulating materials in the region of the plug intended to be grasped by the user. However, such plugs are heavy, bulky and more costly than a plug which is not thermally insulated.

It is against this background that the present invention has been conceived. It is an aim of the present invention to address one or more of the above problems.

Embodiments of the invention may facilitate the recharging of electrically powered vehicles in a domestic environment whilst minimising the duration of the vehicle's recharge time and improving customer satisfaction. In addition, embodiments of the present invention may offer a reduction in plug mass and bulk compared to known systems. Such embodiments may improve user comfort and perceived quality when charging a power storage means such a battery for an electrically powered vehicle. Other aims and advantages of the invention will become apparent from the following description, claims and drawings.

Summary

Aspects of the invention therefore provide a device, an electrical connection, a charging system, a method and a vehicle as claimed in the appended claims.

According to an aspect of the present invention for which protection is sought, there is provided a device for a removable electrical connection between an electrical power supply and an electrical load such as a power storage means, the device comprising: a temperature sensing means; a communication means; and a shroud, wherein the shroud is configured to at least partially support the temperature sensing means in close proximity with at least one electrical conductor within said electrical connection, and said temperature sensing means is arranged to communicate temperature data via the communication means to at least one of said electrical power supply and/or electrical load.

Advantageously, the present invention permits optimisation of the maximum electrical current that may be drawn from a given outlet for an electrical power supply, such as a domestic electrical socket, whilst managing the temperature of an exterior surface of the removable electrical connection. Conveniently, this reduces the likelihood that it becomes uncomfortably hot for a user to handle.

In an example, the device is arranged for integration into an electrical plug.

In an example, the device is arranged for integration into an electrical socket.

Advantageously, the device may be readily adapted for use in either a plug or socket configuration depending on the circumstances.

In an example, the temperature sensing means is arranged to communicate temperature data via the communication means, indicative of the temperature of at least one exterior surface of said plug and/or socket.

Advantageously, this facilitates early detection or even prediction of excessive heating of the electrical connection, whose outer surface temperature is mostly dependent upon the temperature of the electrical conductors carrying the current in use.

In an example, the shroud comprises an electrically conductive element arranged to facilitate electrical communication between the communication means and at least one electrical conductor within said electrical connection.

Advantageously, this minimises the assembly time and attendant costs associated with manufacturing electrical connections.

In another aspect of the present invention for which protection is sought, there is provided an electrical connection comprising at least one electrical conductor and a device according to any preceding paragraph, the electrical connection further comprising a grippable surface configured to facilitate the user gripping said connection by hand for connection to and disconnection from said electrical power supply, and the temperature sensing means is arranged to measure the temperature of at least a portion of the electrical connection whose temperature change is proportional to the temperature of said grippable surface.

In an example, the electrical connection further comprises control means arranged to monitor the temperature measured by the temperature sensing means and to communicate temperature data via the communication means to at least one of said electrical power supply and/or load.

In an example, the control means is further arranged to monitor the voltage supplied by the electrical power supply and to communicate supply voltage data via the communication means to at least one of said electrical power supply and/or load.

Advantageously, monitoring the temperature and voltage facilitates the electrical power supply or electrical load in taking the appropriate action during a charging cycle.

In an example, the control means is arranged to control a status indicator, wherein the control means is arranged to provide an indication to the user as to the temperature of the electrical connection in dependence on said temperature data from the temperature sensing means.

In an example, the control means is arranged to provide an indication to the user as to the supply voltage of the electrical power supply in dependence on said voltage data generated by the control means.

In an example, the control means is further arranged to interrupt current flow through at least one electrical conductor in dependence on receiving temperature data indicative of the temperature of the electrical connection exceeding a pre-determined threshold.

In an example, the control means is further arranged to interrupt current flow through at least one electrical conductor in dependence on receiving voltage data indicative of a fault in either the electrical power supply or said electrical conductor.

Advantageously, the control means may intervene during the charging cycle and limit the electrical current that may be drawn, or even terminate the charge cycle altogether where appropriate, managing the heat build-up in the charge equipment.

In an example, upon the interruption of the current flow through least one electrical conductor by the control means, the control means is arranged to activate said status indicator and to indicate to the user that current flow has been deliberately interrupted by the control means.

In an example, the status indicator is arranged to indicate to the user the reason why the flow of current was interrupted by the control means.

Advantageously, this provides a means to inform the user as to the electrical health of the equipment used, especially the condition of the power outlet, so that the user can take appropriate action to repair defective equipment; or to avoid subsequent re-use of a particular defective power outlet.

In a further aspect of the present invention for which protection is sought, there is provided a vehicle charging system comprising a device or an electrical connection according to any preceding paragraph, the charging system comprising: a vehicle connection arranged to cooperate with a corresponding connection mounted on a vehicle; a charge-point connection arranged to cooperate with a corresponding connection mounted on an electrical power supply; and an electrically conductive cable arranged to connect the vehicle connection to the charge-point connection, wherein the charge-point connection has a grippable surface configured to facilitate the user gripping said connection by hand for connection to and disconnection from said electrical power supply, and the temperature sensing means is arranged to measure temperature data indicative of the temperature of the grippable surface.

In an example, the status indicator is arranged to be visible to the user before the grippable surface is gripped by said user, and wherein the status indicator is further arranged to indicate data comprising any one of: state of charge of said power storage means; temperature of the grippable surface; duration of electrical connection with said electrical power supply; cost of electricity used by the power storage means; customer identification details; vehicle identification details; or maximum current drawn from the electrical power supply.

In a still further aspect of the present invention for which protection is sought, there is provided a method of charging a power storage means for a vehicle having a charge controller, the method comprising: electrically connecting the power storage means to be charged to an electrical power supply with a vehicle charging system having a vehicle connection for connecting to the vehicle, a charge-point connection for connecting to the electrical power supply and an electrically conductive cable connecting the charge-point connection and the vehicle connection together; activating the charge controller in dependence on determining that the vehicle charging system is correctly connected to said electrical power supply; measuring the voltage available from said electrical power supply before initiating a charging cycle; measuring the temperature of the charge-point connection before initiating said charging cycle; the charge controller commencing said charging cycle appropriately to the voltage available from the electrical power supply; measuring the voltage supplied from the electrical power supply during the charging cycle; measuring the temperature of the charge-point connection during the charging cycle; the charge controller comparing: the voltage drop at the electrical power supply; the rate of charge of said power storage means; and the change in temperature of the charge-point connection during the charging cycle; with charging profile data held in a memory means accessed by said charge controller; and in dependence on the rate of change of the electrical voltage drop at the power supply and charge-point connection temperature during the charging cycle, varying the current drawn by the power storage means from the electrical power supply, so as to optimise the rate of charge whilst not exceeding a pre-determined charge-point connection temperature.

Within the scope of this application it is envisaged that the various aspects, embodiments, examples, features and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings may be taken independently or in any combination thereof. In particular, features described in connection with one embodiment are applicable to the other embodiment, except where there is an incompatibility of features.

Brief Descrirtion of the Drawings The present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a side view of an electric vehicle known in the art, along with a known charging plug, positioned adjacent to a corresponding vehicle mounted charging socket; Figure 2 shows a known charging lead for connecting an electric vehicle to a suitably configured power outlet, the charging lead comprising a pair of identically configured charging plugs connected by a coiled length of flexible cable; Figure 3 shows a detailed view of the pin layout of a plurality of electrically conductive elements within the known charging plug shown in Figure 1 and in Figure 2; Figure 4 shows an adapter of a known type, arranged to convert one type of electrical connection to another to facilitate charging from a domestic power outlet; Figure 5a shows a schematic view of a device according to an aspect of the present invention; Figures 5b and 6a to 6c show schematic views of devices integrated into electrical connections according to another aspect of the present invention; Figure 7 shows a schematic view of another example of an electrical connection according to an aspect of the present invention; Figure 8 shows a schematic view of a vehicle charging system according to a further aspect of the present invention; and Figure 9 shows an example of a logic table for use with a vehicle charging system according to an aspect of the present invention.

While the examples given for suitable applications for the present invention relate to equipment for charging electrically powered vehicles, it will be appreciated by one skilled in the art that there are potentially other uses for the present invention unrelated to vehicles, where electric current may be supplied via a disconnectable connection such as power generators, telecommunications devices, compressors or air handler units. The present invention is equally suitable for use with single-phase and multi-phase alternating current AC electrical supplies, and may also be used with direct current DC supplies as desired.

Figure 1 shows an example of an electric vehicle 100 of the prior art, showing the location of a vehicle mounted charging socket 5 behind a hinged cover in the side of the vehicle 100. Also shown in the Figure is a charge connection in the form of a vehicle charge plug 3 of a known type being held by a user adjacent to the vehicle mounted charging socket 5. The vehicle charge plug 3 is arranged to supply electrical power from a power outlet (not shown) to a power storage means such as a battery (also not shown) mounted within the vehicle 100 via a length of electrically conductive cable 7. The charging plug 3 and cable 7 are shown in greater detail in Figure 2.

Figure 2 shows a known vehicle charging lead 2 for connecting an electric vehicle 100 to a suitably configured power outlet or charging point (not shown). In the example shown, the charging lead 2 has a pair of charge connections in the form of a charge point plug 4 and an identically configured vehicle charge plug 3, connected together by a coiled length of flexible cable 7. Each charge connection comprises an exterior surface configured to facilitate gripping by the user. This gripping portion or hand grip 3a, 4a is arranged to facilitate operation of the plug by hand. Each charge connection further comprises an insertion portion 3b, 4b, arranged to cooperate with an associated socket (as shown in figure 1), and a plurality of conductors 3c, 4c. Each conductor 4c within the charge point plug 4 is connected via separate conductive cores in the cable 7 to the corresponding conductors 3c in the vehicle connection 3.

Figure 3 shows an example of a known charge plug with an appropriate layout of conductors. In Europe a consortium of energy providers, local Government and vehicle manufacturers have been working towards a standardised set of specifications for such a plug, an example of which is shown in Figure 3. This example of a vehicle charge plug has been developed by Men nekes ® of Germany as an answer to the demand in the European marketplace for a standardised electric vehicle charging plug.

It may be seen from the Figure that the hand grip 3a of the vehicle charge plug 3 extends downwardly from the insertion portion 3b, arranged to support and at least partly surround the plurality of electrical conductors 3c. The electrical conductors 3c are arranged around a centrally positioned earth pin 3E and are spaced therefrom. It will be appreciated that the body of the hand grip 3a, the insertion portion 3b and the insulating portions 3i between the conductors 3c are formed at least in part from a plastics moulding so as to insulate the user from the electricity conducted by the conductors 3c in use. The charge plug may be formed as an assembly of parts or as a unitary moulding. It will also be noted that there are two lead lines from numeral 31, as the immediate surroundings of each conductor 3c, and the flat end face of the plug, both serve as insulators.

The layout of conductors 3c of the charge plug 3 shown in Figure 3 provides for up to a three-phase electrical connection via three live conductors 3L1, 3L2 and 3L3. In addition, there are provided an Earth pin 3E, a Neutral connection 3N, and two communications connections 3pp, 3cp. The communication connections comprise a connector 3pp arranged to determine that the plug 3 has been correctly connected to the vehicle 100, known as a plug present connector; and a connector 3cp arranged to permit electrical communication between the vehicle 100 and the power outlet in use, known as a control pilot connector.

In the vehicle charge plug 3 shown in the Figure, the insertion portion 3b is formed from a substantially cylindrical section body containing the electrical conductors 3c.

The outer surface of this cylindrical section is substantially circular in section, but is provided with a keyed section or flattened portion 3f, arranged to guide the user to correctly orientate the plug 3 into a correspondingly shaped vehicle-mounted charging socket 5 as shown in Figure 1. It will be appreciated by one skilled in the art that this keyed section may be provided at any point around the outer circumference of the insertion portion 3b, so long at its position corresponds with the conductors 3c correctly aligning with the corresponding conductors in the socket 5. In the example shown, the keyed section or flattened portion 3f is located at the top of the insertion portion 3b so that it may be readily visible and is thus intuitive to the user, guiding them as to the correct insertion orientation of the plug into the socket. Distal from the conductors 3c and the insertion portion 3b is the cable 7, shown depending from a lower portion of the hand grip 3a of the charge plug 3.

A drawback of the vehicle charging lead 2 shown in Figure 2, is that its charge point plug 4 is incompatible with a standard domestic power outlet socket. As such, the user must reconfigure the charging lead 2 to charge from a domestic power outlet by connecting an adapter to the charge point plug 4 so that the charging lead 2 is terminated by a standard domestic power plug 9 at one end and a charging plug 3 at the other.

Such an adapter is shown in Figure 4. Adapter 8 is arranged to facilitate vehicle charging via a standard domestic electrical power outlet (not shown). The adapter comprises a domestic power plug 9 arranged to cooperate with the standard domestic electrical socket used in the market in which the vehicle is to be used.

The adapter further comprises an EVSE (Electric Vehicle Safety Unit) 6, arranged to cooperate with the charge point plug 4 of the vehicle charging lead 2 of Figure 2.

A length of electrical cable 7a electrically connects the EVSE 6 and the domestic power plug 9. The adapter is used when a dedicated vehicle charging point is not available, and the user must therefore charge the vehicle 100 by connecting it to a standard domestic power outlet. Although a British Standard 13 amp, 3-pin plug is shown, any national or international mains power plug could be used here.

In the adapter 8 shown in Figure 4, the EVSE 6 comprises a receiving section 6b and conductors 6c arranged to cooperate with a Live conductor 4L1, a Neutral connection 4N and an Earth connection 4E of the charge point plug 4. The conductors of the charge point plug 4 are not shown in detail in the Figures, but are arranged substantially identically to those of the vehicle charge plug 3 shown in Figure 3. The receiving portion 6b is arranged to accommodate the insertion portion 4b of the charge point plug 4. The receiving portion 6b is further provided with an alignment guide (not shown, but similar to flattened portion 3f in Fig. 3) to ensure that the user correctly aligns the conductors of the plug 4 and socket 6 before use. The EVSE 6 may further comprise a grippable portion or handle (not shown) to allow it to be held while plug 4 is inserted into receiving portion 6b.

In view of the size and shape of the EVSE -approximately equivalent to a shoe box -an alternative embodiment, not shown in the Figures, may be considered to be preferable. In this case, the EVSE 6 has a further fly lead at the end of the unit distal from cable 7a, which connects to a socket compatible with plug 4. The EVSE is thus allowed to lie on the ground, avoiding the need to handle its weight and bulk while making and maintaining an electrical connection.

It will be appreciated that the standard domestic power outlet and associated power plug 9 are primarily intended for use with general domestic appliances, and are therefore not optimised for the relatively high current demand typically associated with charging electric vehicles. If the distance between the power outlet and the consumer unit of the residence is relatively long, it will result in significant electrical losses in the wiring. Such losses adversely affect the available rate of charge for the electrically powered vehicle, increasing recharge times.

Plugs and sockets used in conjunction with domestic power outlets have a rated maximum continuous current related to the electrical resistance of the plug and socket components. The voltage supplied to these domestic outlets may vary from one market to another or even within a single market. Such variation is relatively simple to accommodate from the point of view of a vehicle designer by measuring the voltage available from the outlet upon initial connection with the vehicle.

However, one variable that will affect charging of an electrically powered vehicle is the available current.

Over time, electrical components within the plug and socket tend to oxidize, increasing their electrical resistance and potentially resulting in damage due to excess heating during the charge cycle even if the rated current is not exceeded.

Even if the heating of the outlet is not sufficient to cause permanent damage, the temperature of the outlet may exceed what is comfortable for the user to handle. In this case, it may become uncomfortable or difficult for the user to disconnect the electrical connection once the vehicle charge cycle has been completed.

Uncomfortably high temperatures do not normally result in any change of appearance of the outlet which would indicate this to the user. In this case, the user may inadvertently grasp the electrical connection or outlet and, upon feeling the temperature of the part, become concerned that there was a malfunction in the equipment.

In some cases, manufacturers of electric vehicles and their associated charging equipment manage the problem of excess heat build-up in the connection and outlet by limiting the charge current to a fraction of the rated charge current of the outlet. Whilst this does tend to keep the heat build-up in the connection and outlet within acceptable limits, it adversely affects the charging cycle time, which might otherwise be shorter if the charging current was not limited in this way. Whilst some users may not experience excess heating of the electrical connection or outlet during charging, especially if the outlet or electrical connection is not corroded, an extended charge cycle time may be a problem to users wishing to charge their vehicle quickly.

In the example of the adapter 8 shown in Figure 4, the domestic power plug 9 is of a standard form configured for connection to a single phase electrical supply and thus comprises a body portion or casing 9b within which three electrical conductors 9c are mounted, and protrude outwardly therefrom. The three electrical conductors 9c are required to provide the power plug 9 with separate conductors for Live, Neutral and Earth connections, interfacing with the typical domestic power outlet socket. The body portion 9b is generally square in cross section and arranged to facilitate manual connection to and disconnection from the electrical outlet. It is known to produce power plugs 9 as an assembly, screwed or clipped together once the plug 9 has been fitted to the cable 7a. It is also known to over-mould the plug 9 onto the cable to produce a sealed, unitary component.

In order to keep the duration of the charging cycle to a minimum, the current drawn by the vehicle must be held as close as possible to the maximum rated current capacity of the power outlet. Any ramping up to or down from this maximum current value must be done as quickly as possible to permit the electrical power storage means, such as a battery of the vehicle, to draw sufficient charge as quickly as possible. Dedicated vehicle charging outlets are specifically configured to meet these current demands and are often direct current (DC) voltage rather than alternating current (AC) voltage to gain further benefits in reducing the charge cycle time. However, when relying on existing domestic electrical infrastructure, the distance from the electrical supply into the building and the condition of the electrical cables are often not optimised for such a potentially high current electrical load.

Where the power outlet and plug being used to charge the vehicle are in good condition, the power outlet and associated domestic power plug 9 may only become warm to the touch during the charge cycle. However, if the condition of the power outlet or plug is poor, the temperature of the domestic power plug 9 may increase to a level which may be uncomfortable for the user to handle. This may lead to a false perception that some component within the vehicle, charging lead or power outlet is unsafe; or that the electrical equipment in question is defective.

The present invention seeks to address these issues, whilst at the same time facilitating charge cycle times which are optimised for the power outlet being used.

The present invention provides the benefit of being compatible with a plurality of vehicles, power outlet configurations and voltage supplies, and does not rely on access to a dedicated vehicle charging station.

Figure 5 shows devices 10 and 410 embodying two forms of the present invention.

Figure 5a shows an example of the device 10 arranged for use with a typical three-pin mains voltage plug used for domestic electrical appliances in the United Kingdom. Figure Sb shows an example of the device 410 adapted for integration within an electrical connection such as a vehicle charge plug 3 or charge point plug 4 as shown in Figure 1 and in Figure 2. It will be appreciated that the shape and size of the device 410 may be readily adjusted to be accommodated within electrical plugs for use in other markets.

In the example shown in Figure 5a, the device 10 takes the form of a generally U-shaped plate 16 arranged to be accommodated at least partially within the body portion of a standard three-pin plug. The first leg 16i and second leg l6ii form a planar and substantially continuous U' shape configured to rest against an inner surface of a front face of the power plug.

The legs I 6i, I 6ii of the U-shaped plate 16 include respective apertures I 6Na and l6La, through which the neutral and live conductors (also known as pins) of the plug are arranged to extend. A third aperture 1 6Ea is provided at the intersection or apex of the legs 16i, I 6ii to accommodate the earth conductor of the plug. The apertures l6Na, l6Ea, and l6La are preferably sized and shaped so as to remain in thermal contact with the relevant electrical conductor within the power plug.

However, only one of these three apertures should be in electrical contact with a conductor, the other apertures being electrically isolated to avoid short circuits.

The first and second legs 16i, l6ii of the plate 16 are arranged to support at least one temperature sensing means 12, in the form of a thermistor, thermocouple or other suitable device, in close proximity to at least one of the electrical conductors within the power plug (not shown). Alternatively, in further embodiments not shown in the Figures, the temperature sensor may be bonded directly to the live pin, or clamped by a crimp joint or screw terminal provided to anchor the live wire.

Associated with the temperature sensing means 12 is a communication means 14 for communicating temperature data to a controller (not shown). The temperature sensing means 12 is arranged to determine the temperature of the electrical conductor, and to transmit this temperature data via the communication means 14 to at least one of an electrical power supply and/or electrical load (not shown).

Alternatively, the temperature sensing means may be arranged to measure the temperature of a part of the removable electrical plug or socket in which the device lOisinstalled.

In the illustrated embodiment, the plate 16 also comprises a third leg l6iii extending generally orthogonally from the intersection of the first and second legs 16i, l6ii, adjacent to the aperture l6Ea. The third leg l6iii is curved at its free end so as to extend in a substantially planar configuration, parallel with the first and second legs 16i, l6ii and spaced therefrom. The tip 16T of the third leg l6iii is arranged to lie in close proximity with an inner surface of a rear face of the body portion of the plug, being the portion gripped by the user during connection to and disconnection from the power outlet. The tip 1 6T of the third leg 1 6iii may support a second temperature sensing means (not shown) for detecting the temperature of the external surfaces of the body portion of the plug. In this arrangement, the device 10 is capable of measuring the temperature of both the electrical conductors and an exterior surface such as a hand grip in use.

The temperature sensing means 12 may be passive, or may be supplied with power from the conductors within the plug. Alternatively, the temperature sensing means 12 may be powered via a connection to a vehicle, connected to the power outlet via the removable electrical connection. It is also envisaged that the temperature sensing means 12 may be powered by a low voltage battery (not shown), accommodated within the plug. Preferably, the battery would be rechargeable and may be recharged whenever an electrical current passes through the electrical connection during the charging cycle. In this way, the battery provides a back-up source of power for the temperature sensing means 12 if the power supply is temporarily interrupted.

It will be appreciated that the device 10 may be readily adapted for use in electrical connections of a more specialist nature, such as those intended for dedicated charging stations.

Figure 5b shows an example of a device 410 adapted for integration into an electrical connection such as charge point plug 400, shown in Figure 7. The body of plug 400 comprises three distinct elements, being a main body 405M, arranged to fit between the electrical conductors, an upper body 405U and a lower body 405L.

The upper body 405U is arranged to support a temperature sensing means 412U close to the outer surface of an insertion portion 400b formed in the electrical connection 400 as shown in Figure 7. The lower body 405L is arranged to support a temperature sensing means 412L close to the outer surface of a hand grip feature (400a, Fig. 7) formed in the electrical connection 400. Arranged around a substantially centrally positioned aperture 4lOEa, configured to fit around an Earth connection in the electrical connection 400, is a third temperature sensing means 412E. Temperature sensing means 412E is supported by the main body 410M, and is positioned to facilitate reliable measurement of the temperature not only of the conductors in the electrical connection 400 in which the device 410 is accommodated; but also of the temperature of the power outlet to which said electrical connection is connected. Similarly, temperature sensing means 412U and 412L are positioned so as to facilitate reliable measurement of the surface temperature of external surfaces of the electrical connection 400 which the user may handle in use.

The main body 410M is provided with a plurality of apertures 4lOca, each aperture being arranged to accommodate a portion of an electrical conductor. Two additional apertures 4lOppa and 4lOcpa are provided in the main body 410M to accommodate a portion of the plug present (pp) connector and the control pilot (cp) connector respectively.

The temperature sensing means are each in communication with a communication circuit 414 arranged to process temperature data measured by the temperature sensing means; and to communicate that data via one or more of the conductors in the electrical connection 400. In the example shown, temperature data is communicated to a charge controller (not shown) via the plug present (pp) and the control pilot (cp) lines as required.

Figure 6a shows a view through an electrical connection in the form of a power plug 90 in which a device 110 similar to the device 10 of Figure 5a is installed. A different reference numeral is used because it is envisaged that device 110 will have additional features such as screw holes which are not shown in device 10 in Figure 5a. In this example, the power plug 90 is of a type suitable for connection to a standard 13A domestic power outlet in the United Kingdom. Preferably, the device 110 is integrated into the electrical connection as an over-moulded part.

However, it is envisaged that the device 110 may be fitted into the electrical connection as part of an assembly, arranged to be held together by threaded fasteners, clips, heat staking and/or adhesives as may be appropriate.

In the example, the power plug 90 comprises a cover 90a arranged to enclose a body portion 90b extending from a connector portion 90c arranged to support a plurality of electrical conductors 90cc, of which the live conductor 90L and the earth conductor 90E can be seen in this view. (the neutral connector 90N being concealed behind live conductor 90L). In the example, the power plug 90 is shown with a cable 70 entering the body 90b of the plug 90. The cable 70 is secured to the plug 90, either by means of a clamp (7OCL, Fig. 6b) or by over-moulding the plug 90 to the end of the cable 70 during manufacture.

It may be seen from the Figure that the plate 116 (similar to plate 16 in Fig. 5a) is arranged to lie against the inner surface of the front face of the plug 90 so as to be in close proximity with an outer surface of the outlet (not shown) into which the power plug 90 is inserted in use. It may also be seen from the Figure that the third leg 11 6iii of plate 116 is arranged to abut the inner surface of the cover 90a of the plug 90.

It is envisaged that the temperature sensing means 112 (not shown in Figure 6a) may be located at any suitable position on any of the legs ll6ito ll6iii of the device 110. Indeed, the device 110 may be arranged to support a plurality of temperature sensors so as to measure temperature changes at various locations within the plug in use, or to measure the difference in temperature between different positions around the connection as desired. Figure 6b shows a rear view of the plug 90 of Figure 6a, and shows the device 110 in situ. Numeral 70CL denotes a cable clamp for cable 70. Numeral 90F denotes a fuse fitted to live terminal 90L.

Figure 6c shows another example 210 of a device according to an aspect of the present invention. The device 210 is shown accommodated within a power plug 290 having a form identical to that of plug 90 of Figures 6a and 6b. The device 210 is similar to the device 110 shown in Figure 6b in that it has a substantially U' shaped form. As with the device 110 of Figure 6b, the device 210 is arranged to abut, or to be integrally formed with, a connector portion 290c of the plug 290. The plug 290 comprises a plurality of electrical conductors, providing Neutral (290N), Earth (290E) and Live (290L) electrical conductors in use.

A single temperature sensing means 212 is located between one of the electrical conductors 290N (as shown) or 290L and the Earth conductor 290E; and is located adjacent to communication means 214. The communication means 214 is arranged to send temperature data via a data line 214a. The data line 214a is provided by a conductive core forming part of a main cable 270 arranged to connect the plug 290 to an electrical load such as an electric vehicle or to a controller (not shown).

Figure 7 shows the device 410 of Figure 5b integrated into an electrical connection 400. The connection 400 comprises a hand grip 400a, an insertion portion 40Db, and a plurality of conductors 400c. It may be seen from the Figure, that the temperature sensing means 412U, 412L and 412E are positioned to measure the surface temperatures of the upper and lower parts of the hand grip 400a and the temperature of the conductors 400c respectively.

Figure 8 shows an example of a vehicle charging system 700 according to a further aspect of the present invention. The vehicle charging system 700 comprises a vehicle charging plug 3 connected by a length of electrically conductive cable 7 to a charge point connection 400. The charge point connection 400 comprises a device 410 as described in the preceding paragraphs and according to an aspect of the present invention. The vehicle charging plug 3 is shown in engagement with the vehicle 200 via the vehicle mounted charging socket 5. The charge point connection 400 is shown being positioned for insertion into a power outlet at a vehicle charging station 44.

In the example shown, a controller 77 is integrated into the vehicle charging system 700. The controller 77 may be integrated into the charge point connection 400 or into an in-line receptacle located along the length of the electrically conductive cable 7. The controller 77 comprises a microprocessor 75 configured to monitor temperature data from any temperature sensing means in operation within the charge point connection 400. The microprocessor 75 of the controller 77 is further configured to limit the electrical current drawn by the vehicle 200 during a charge cycle in dependence on the temperature data received from said temperature sensing means.

In the example, the vehicle charging system 700 comprises at least a section of cable capable of communicating temperature data to the controller 77. This section of cable, shown generally at 70a, may be limited between the charge point connection 400 and the controller 77; or may run the full length of the cable 7 so as to permit monitoring of the temperature data by systems on-board the vehicle 1.

The charge point connection 400 shown in the example is provided with an integrated means of indicating the status of at least one parameter of the charge point connection 400. An integrated status indicator 450 may be provided by a visible or audible indication to the user. It is envisaged that this status indicator will be provided by at least one of the following: a light emitting diode LED, a display comprising a plurality of LED's, a liquid crystal display LCD, or a sound emitting device such as a buzzer. The status indicator 450 is arranged to warn the user if the temperature of an exterior surface of the charge point connection 400 exceeds a pre-determined threshold. Depending on the configuration of the controller 77, the status indicator may also be arranged to display information such as the maximum charging current drawn during the charge cycle, the duration of the charge cycle and whether the controller 77 imposed a limit on the charging current due to excessive heating of the charge point connector 400.

Figure 9 shows an example of a logic table used by the controller 77 of the vehicle charging system 700 of Figure 8. In this example, the microprocessor 75 within the controller 77 is provided with a memory in which to store the logic table shown.

The logic table is used by the controller 77 to control the status indicator 450 and the current drawn during the charging cycle in dependence on the temperature of the charge-point connection. The controller 77 is activated upon initiation of the charge cycle; the charge cycle being initiated once the vehicle 200 and power outlet 44 are correctly connected by the vehicle charging system 700.

In this example, the controller 77 monitors the surface temperature of the charge-point connection, and uses four bands of increasing temperature upon which to make a decision. The first temperature band, band I represents a surface temperature of up to approximately 25°C. Band 2 represents a surface temperature up to approximately 45°C. Band 3 ranges up to around 60°C; while a surface temperature over 60°C falls into band 4. In practice, some hysteresis would be built in, for example switching from band 1 to band 2 at 23-27°C, so that the controller is not switching continuously.

It may be seen from the table that the controller 77 takes no action to limit the flow of current to the vehicle 200 up to the temperature limit of band 2. Instead, the controller 77 drives the status indicator 450 to provide an indication to the user as to the temperature of the charge-point connection and/or the state of charge of the vehicle 1. If the surface temperature of the charge-point connection rises to temperature band 3, the controller 77 will incrementally limit the current drawn until the temperature falls back within temperature band 2; then slowly increases the current drawn until the measured temperature remains constant. At this point, the controller 77 determines that the maximum current is being drawn from the power outlet 44 in use when the temperature of the charge-point connector remains within acceptable limits for comfort. If the surface temperature of the charge-point connection rises quickly during the charging cycle, the surface temperature may exceed the limits of band 3. Alternatively, the controller 77 may predict that, given the rate of change of temperature, measured by the temperature sensing means in the charge-point connection, there is a significant probability of an electrical fault in the outlet 44. At which point, even if the measured surface temperature does not exceed band 3, the controller will immediately shut-down the charging cycle and generate an appropriate warning via the status indicator, such as flashing red to indicate a fault.

It is envisaged that the controller is arranged to wait until the surface temperature of the charge-point connection falls within temperature band 2 before attempting to re-initialize a charging cycle. If the same fault occurs more than a pre-determined number of times, the controller 77 may be arranged to notify the vehicle 200 which may be equipped with means to notify the user, by generating an automated message to the user via a text message or E-mail etc. In an embodiment of the present invention, the controller 77 is arranged to monitor the temperature data and the supply voltage provided by the power outlet 44 during the charge cycle. In this case, once activated, the controller 77 is arranged to measure the voltage available from the power outlet 44 before permitting current flow. The controller 77 then stores the initial temperature reading from each temperature sensing means to determine the temperature of the charge-point connection. A charge controller (not shown) will determine the available voltage from the power outlet 44 and identify the active conductors in the vehicle charge plug. The appropriate charging current and an appropriate charging cycle will then commence.

During the charging cycle, the controller 77 monitors the voltage supplied by the power outlet 44 and measures the temperature data from the temperature sensing means in the charge-point connection. The controller 77 compares: the voltage drop at the power outlet 44; the rate of charge of said power storage means; and the change in temperature of the charge-point connection during the charging cycle with a list of charging profiles held in the memory. In dependence on the rate of change of the voltage drop at the power outlet 44 and temperature of the charge-point connection during the charging cycle, the controller 77 is arranged to vary the current drawn by the vehicle from the electrical power supply, so as to optimise the rate of charge whilst not exceeding a pre-determined temperature threshold of the charge-point connection.

It will be appreciated by one skilled in the art that aspects of the present invention may be adapted to equipment arranged to comply with existing and future regulations relating to the charging of electrical vehicles. An example of which would be the IEC Regulations, concerning current control during the charging cycle and specifically defining modes of current control during charging. It will be appreciated that the device and associated temperature sensing means may be integrated into a mains electric socket, into the charging lead, or into alternative arrangements of in-line and vehicle mounted electrical connections. Furthermore, the invention may be applied to other high current electrical equipment, for reasons of comfort, user confidence, and/or safety.

Other advantages will be apparent to one skilled in the art and the present examples and embodiments are to be considered illustrative and not restrictive.

The invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.

For example, although data line 214a and communication circuit 414 are shown as electrical cables, the signals sent therethrough could be converted to light signals, and communicated via fibre optic cables. Alternatively, data could be transmitted by radio signals. Furthermore, the EVSE unit 6 shown in Figure 4 may contain the controller 77 of Figure 8, or vice versa.

Claims

CLAIMS1. A device for detecting the temperature of at least part of an electrical connection such as a plug or socket, the device comprising: temperature sensing means; and support means for supporting the temperature sensing means in close proximity to at least one electrical conductor within said electrical connection.
2. A device as claimed in claim 1, comprising communication means arranged to communicate temperature data from the temperature sensing means to at least one of a controller, an electrical power supply and an electrical load.
3. A device as claimed in claim I or claim 2, wherein said device is arranged for integration into an electrical plug.
4. A device as claimed in claim I or claim 2, wherein said device is arranged for integration into an electrical socket.
5. A device as claimed in any preceding claim, wherein the support means is arranged to support the temperature sensing means adjacent at least one surface of the electrical connection, so as to measure the temperature thereof.
6. A device as claimed in any of claims 2 to 5, wherein the support means comprises an electrically conductive element arranged to permit electrical communication between the communication means and at least one electrical conductor within said electrical connection.
7. An electrical connection such as a plug or a socket, comprising a device as claimed in any preceding claim.
8. An electrical connection as claimed in claim 7, comprising control means for monitoring the temperature measured by the temperature sensing means and for communicating temperature data via the communication means to at least one of an electrical power supply and/or electrical load.
9. An electrical connection as claimed in claim 8, wherein the control means is arranged to monitor the voltage supplied by the electrical power supply and to communicate supply voltage data to at least one of said electrical power supply and/or electrical load.
10. An electrical connection as claimed in claim 8 or claim 9, wherein the control means is arranged to provide an indication to a user of the temperature of the electrical connection in dependence on the temperature data from the temperature sensing means.
11. An electrical connection as claimed in claim 1 0, wherein the control means is arranged to provide an indication to the user of the supply voltage of the electrical power supply in dependence on the voltage data generated by the control means.
12. An electrical connection as claimed in any one of claims 8 to 11, wherein the control means is arranged to interrupt current flow through at least one electrical conductor in dependence on the temperature of the electrical conductor as detected by the temperature sensing means exceeding a p re-determined threshold.
13. An electrical connection as claimed in any one of claims 8 to 12, wherein the control means is arranged to interrupt current flow through at least one electrical conductor in dependence on the detected voltage indicating a fault in either the electrical power supply or the electrical conductor.
14. An electrical connection as claimed in claim 12 or claim 13, wherein upon the interruption or the current flow through least one electrical conductor by the control means, the control means is arranged to indicate to the user that current flow has been interrupted by the control means.
15. An electrical connection as claimed in claim 14, comprising a status indicator arranged to indicate to the user the reason why the flow of current was interrupted by the control means.
16. A charging system for a vehicle comprising: a first plug arranged to cooperate with a corresponding first socket mounted on a vehicle; a second plug arranged to cooperate with a corresponding second socket of an electrical power supply; and a cable connecting the first and second plugs; wherein at least one of the first and second plugs and the first and second sockets comprises a device or an electrical connection as claimed in any preceding claim.
17. A charging system as claimed in claim 16, wherein one or both of the first and second plugs includes a portion arranged to be gripped by the user during connection to and disconnection from the respective first or second socket, and wherein the temperature sensing means is arranged to communicate temperature data indicative of the temperature of the grippable portion.
18. A charging system as claimed in claim 16 or claim 17, wherein one or both of the first and second plugs comprise status indicator means disposed so as to be visible to a user and arranged to indicate data comprising any one of: a state of charge of a power storage means of the vehicle; a temperature of at least one of the first and second plugs and the first and second sockets; a duration of electrical connection between the electrical power supply and the vehicle; a cost of electricity used by the power storage means; customer identification details; vehicle identification details; and a maximum current drawn from the electrical power supply.
19. A method of charging a power storage means of a vehicle using a charging system as claimed in any one of claims 16 to 18, the method comprising: measuring the voltage available from said electrical power supply and/or the temperature of the second plug before initiating a charging cycle; commencing said charging cycle appropriate to the voltage available from the electrical power supply; measuring the voltage supplied from the electrical power supply and/or the temperature of the second plug during the charging cycle; comparing at least one of the voltage drop at the electrical power supply, the rate of charge of said power storage means and the change in temperature of the charge-point connection during the charging cycle with profile data held in a memory; and in dependence on the rate of change of the electrical voltage drop at the power supply and/or the temperature of the second plug during the charging cycle, varying the current drawn by the power storage means from the electrical power supply so as to optimise the rate of charge whilst not exceeding a pre-determined charge-point connection temperature.
20. A vehicle having a device or an electrical connection as claimed in any one of claims 1-15, or adapted to use a charging system or a method as claimed in any one of claims 16-19.
21. A device, an electrical connection, or a charging system constructed and arranged substantially as described herein with reference to figures 5 to 9 of the accompanying drawings.