Electric vehicle supply apparatus

Abstract

An electric vehicle (EV) supply apparatus (EV charger 2) includes: a socket 4 for receiving an electrical plug 6 along an insertion axis 8; a plunger 10; and a control system 24. The plunger is config

Description

Electric Vehicle Supply Apparatus BACKGROUND OF THE INVENTION This invention relates to an electric vehicle supply apparatus and an electric vehicle supply system. Electric vehicle supply apparatus, such as an electric vehicle (EV) charger, is used to supply electrical power to plug-in electric vehicles for charging batteries within the vehicles. Charging units can be “tethered” (having a permanently-attached charging cable) or “untethered” (having a socket to which a separate charging cable can be connected by the user). It is known for “untethered” electric vehicle supply apparatus to have a sensor for ensuring that the electrical plug of the charging cable is fully inserted within the socket before electrical power is supplied through the socket. However, such sensors can register false detections, e.g. a result of an error or tampering with the device, and this can result in power being supplied through the electrical socket at a time when it is dangerous to do so. The present invention seeks to provide safer EV supply apparatus. SUMMARY OF THE INVENTION From a first aspect, the invention provides an electric vehicle supply apparatus comprising: a socket for receiving an electrical plug along an insertion axis; a plunger, configured to move within the socket, at an angle to the insertion axis, as a result of contact between the plunger and the electrical plug as the electrical plug is inserted into the socket: and a control system configured to: detect when the plunger reaches a first extent, outward from the insertion axis, indicative of the electrical plug being partially inserted within the socket: determine that the plunger is at a second extent, outward from the insertion axis, wherein the second extent is less than the first extent, and wherein the second extent is such that, when the electrical plug is fully inserted into the socket, the plunger is at the second extent; and activate a supply of electrical power through the socket only when the plunger is at the second extent after having previously reached the first extent. According to a second aspect, the invention provides an electric vehicle supply system, comprising: electrical vehicle supply apparatus as disclosed herein; and an electrical plug for insertion in the socket of the electrical vehicle supply apparatus. Thus it will be seen that, in accordance with embodiments of the invention, by detecting when the plunger reaches a first extent and by then determining that the plunger has subsequently reached a second extent, less than the first extent, and activating supply of power only when this occurs, the risk of activating power supply at an inappropriate time may be reduced. In particular, the electric vehicle supply apparatus not only determines that the plunger is at a second extent, the second extent being the extent that the plunger is at when the plug is fully inserted, but it also checks that, prior to being in this state, the plunger has also reached a first, greater extent that is indicative of the plug being partially inserted. This can prevent the supply of power from being activated in the situation where the plunger is in a state corresponding to full insertion of the plug, but without the plug actually being fully inserted, for example due to tampering with the device or a mechanical fault. The first extent being further out than the second extent reduces the likelihood of the plunger reaching the first extent other than through typical insertion of the plug. This helps to reduce the chance of supplying power through the socket at a time when it would be inappropriate, and possibly dangerous, to do so. The electrical plug may be coupled to a charging cable for supplying electrical power to an electric vehicle. The EV supply apparatus may be an untethered EV charger. It may comprise a housing which may contain the control system. The socket may be mounted on a surface of the housing. The control system may be configured to indirectly determine (i.e. infer without direct measurement), based on one or more other detected states or events, that the plunger is at a second extent, or the control system may be configured to directly detect when the plunger is at a second extent (i.e. by direct detection of the plunger, for example using a position sensor). In some embodiments, it may be configured to make both a direct determination and an indirect determination. In some embodiments, the control system determining that the plunger is at the second extent may comprise the control system detecting that the plunger is no longer at the first extent. This alone may be sufficient to infer that the plunger is at the second extent in some embodiments, or the control system may be configured to make the determination based on additional data. It will be understood that, in embodiments in which the control system indirectly determines that the plunger is at the second extent, a state or event that is detected to indicate indirectly that the plunger is at the second extent may arise or occur simultaneously with the plunger moving to the second extent, or it may arise or occur before or after the plunger has moved to the second extent. Optionally the detected state or event may arise or occur (or be required to arise or occur) within a threshold amount of time in advance of or after the plunger moving to the second extent. It will be appreciated that, although the plunger should be at the second extent when the electrical plug is fully inserted, this may not be the only condition under which the plunger is at the second extent. For example, the apparatus may be arranged such that the plunger may also be at the second extent when the electrical plug is fully removed from the socket. Thus, in some embodiments, the position of the plunger at the second extent is not determinative of the electrical plug being fully inserted. In some embodiments, the control system comprises an insertion detection sensor, independent of the plunger, for determining that the electrical plug is fully inserted within the socket. The electric vehicle supply apparatus may be configured to activate the supply of electrical power through the socket only when both conditions are met that: i) the plunger is at the second extent after having previously reached the first extent: and ii) the control system has detected, using the insertion detection sensor, that the electrical plug is fully inserted within the socket. As explained above, a state or event detected by the insertion detection sensor need not arise or occur simultaneously with the arrival of the plunger at the second extent. Embodiments may require any one or more of the various conditions disclosed herein to be met, in addition to the essential condition that the plunger is at the second extent after having previously reached the first extent. The insertion detection sensor may be provided by any sensor suitable for detecting that the electrical plug has reached a fully-inserted position within the electrical socket. The insertion detection sensor may comprise an optical sensor, a capacitative sensor, a magnetic sensor, or a mechanical switch. The insertion detection sensor may comprise an electrical contact, optionally arranged to detect insertion of the electrical plug into the socked based on a change in voltage at the electrical contact, or based on a change in current flow through the electrical contact. In some embodiments the insertion detection sensor comprises a contact sensor, arranged to detect contact between a first portion of the electrical plug and a first portion of the socket indicative of the electrical plug being fully inserted within the socket. The contact between the first portion of the electrical plug and the first portion of the socket may occur simultaneously with the movement of the plunger to the second extent, or may occur before this, or may occur after this. This will depend (at least partly) on the geometry of the electrical plug and the socket. The first portion of the plug may be a distal portion (i.e. located towards an insertion end of the plug). It may comprise part or all of an electrical pin. The pin may be a signalling pin. It may be a control pilot pin. The first portion of the socket may be located within a channel or cavity of the socket. The first portion of the socket may comprise part or all of an electrical connector, which may be a signalling connector. It may be a control pilot connector. The channel or cavity may be arranged (i.e. sized and / or positioned) to receive the aforesaid pin of the plug. The contact sensor may detect contact of a pin of the plug with a connector of the socket. The contact sensor may be a switch or pressure sensor; alternatively it may be an electrical sensor (e.g. a voltage measurement device). It may comprise detection circuitry. The detection circuitry may be configured to detect communication of a control pilot signal between the plug and the socket. The detection circuitry may be configured to detect a change in voltage, and to detect contact between a first portion of the electrical plug and a first portion of the socket based on this change in voltage (e.g. where the change in voltage results from contact between a pin of the plug and a connector of the socket). The change may be a reduction in voltage value (e.g. any reduction), or may be a reduction to one or more defined values, for example a drop from 12V to 9V, 8V or 3V. It will be understood that a change of voltage resulting from connection of the control pilot pin is indicative of connection of an electric vehicle to the other end of a charging cable comprising the electrical plug. A situation may occur in which the electrical plug of a cable is first inserted into the socket, and only later is the plug at the other end of the cable connected to an electric vehicle. In this case, an indirectly determination of the movement of the plunger to the second extent may only be made once the cable is connected to the electric vehicle. Thus, the time allowed between the plunger reaching the first extent and the plunger being determined to be at the second extent may be relatively long, in order to accommodate this scenario. It will be understood that a fully-inserted state, as referred to herein, may describe a position in which the electrical plug is inserted sufficiently far into a socket that a control pilot pin of the electrical plug makes physical and / or electrical contact with a corresponding connector of the socket. Depending on the plug and socket design, this may occur a short distance (e.g. a few millimetres) before a point at which the plug can be pushed no further into the socket. As laid out above, the control system may detect that the plunger is no longer at the first extent. In some embodiments, determining that the plunger has been at the first extent but is no longer at the first extent, together with the control that the electrical plug is fully inserted, may be sufficient for the supply apparatus to make a determination that the plunger is at the second extent. In some embodiments, the control system further comprises a proximity sensor, arranged to detect when the plunger is at the first extent. The proximity sensor may comprise an optical sensor, a capacitative sensor, a magnetic sensor, a mechanical switch, an electrical contact or any other mechanism for determining proximity. The plunger may comprise a reference feature that the proximity sensor can sense (e.g. a magnetic part). The proximity sensor may be located on the travel path of the plunger, e.g. along the line that the plunger moves along, just at or above the first extent, such that a distal end of the plunger (and optionally therefore a feature located thereon) is adjacent to the proximity sensor when the plunger is at the first extent. The proximity sensor may output a simple binary determination that either the plunger is at the first extent (e.g. being within a threshold distance of the proximity sensor) or that the plunger is not at the first extent (e.g. being greater than a threshold distance from the proximity sensor). There may be some tolerance in this determination, such that the first extent may encompass a small range of positions (e.g. within a few micrometres or millimetres). In some embodiments, the plunger being at the second extent is determinative of the plug being fully inserted. It will be appreciated that in such embodiments, the detection that the plunger is at the second extent is sufficient to determine that the electrical plug is fully inserted, e.g. where the second extent can only be reached by the plunger when the electrical plug is fully inserted (such as may occur depending on the shape of a profiled surface of the electrical plug, discussed in greater detail below). The plunger is preferably constrained to move linearly along a plunger axis—e.g. by a housing or guide of the socket. In some embodiments, the control system comprises a position sensor, arranged to determine a distance of the plunger along its direction of movement. In contrast to a binary proximity sensor, the position sensor may be able to distinguish between three or more different positions of the plunger. The position sensor may be arranged to detect when the position of the plunger corresponds to the second extent, and thereby to detect that the electrical plug is fully inserted within the socket. In some embodiments the electric vehicle supply apparatus is configured to activate a supply of electrical power through the socket only when (i.e. not unless) the plunger is at the second extent at a second time after having previously reached the first extent at a first ime, wherein the time between the first time and the second time is lower than a threshold amount of time. In embodiments in which the plunger being at the second extent is determinative of the plug being fully inserted, there may thus be a single threshold amount of time (i.e. a single amount of time within which the plunger must first be detected at the first extent and must subsequently be detected at the second extent). Similarly, in embodiments in which the control system separately detects that the electrical plug is fully inserted, using the insertion detection sensor, there may be a single (cumulative) threshold amount of time, i.e. in a threshold amount of time following detection of the plunger at the first extent, it must be detected both that the plunger has moved away from the first extent, and also that the electrical plug is fully inserted. Thus, the electric vehicle supply apparatus may be configured to activate a supply of electrical power through the socket only when (i.e. not unless) the insertion detection sensor detects full insertion of the electrical plug plunger at a third time after having previously detected the plunger reaching the first extent at a first time, wherein the time between the first time and the third time is lower than a third, cumulative threshold amount of time. The threshold amount of time may have a value of at least 1, 5, 15 or 30 seconds, 1 minute, 5 minutes or 10 minutes and / or of at most 10 minutes, 5 minutes, 60, 30, 15 or 5 seconds. It may be at least as long as a user takes to insert the plug into the socket in normal usage. The control system may comprise a timer for timing a time period starting when the plunger reaches the first extent. The provision of a “timeout” condition means that the plunger having reached the first extent does not mean that an occurrence of the plunger reaching the second extent, and the electrical plug being fully inserted, is sufficient for activation of the power supply however much later this occurs (e.g. even if it is on a later day); rather the plunger must pass through the first extent and then reach the second extent within a realistic period of time in order for the supply of power to be activated. Additionally, or alternatively, there may be separate threshold amounts of time assigned to each of those detection stages. In other words, the electric vehicle supply apparatus may be configured to activate a supply of electrical power through the socket only when (i.e. not unless) the plunger moves away from the first extent at a second time after having previously reached the first extent at a first time, wherein the time between the first time and the second time is lower than a first threshold amount of time. The first threshold amount of time helps to prevent the supply of power from being activated if the plunger has spent a long amount of time at the first extent, outward of the insertion axis. This is helpful since such a condition is likely to be indicative of a fault with the plunger, which might cause a failure of a locking mechanism provided by the plunger. Additionally, or alternatively, the electric vehicle supply apparatus may be configured to activate a supply of electrical power through the socket only when (i.e. not unless) the insertion detection sensor detects full insertion of the electrical plug plunger at a third time after having previously detected the plunger moving away from the second extent at a second time, wherein the time between the second time and the third time is lower than a second threshold amount of time. The second threshold helps to ensure that partial insertion of the plug, followed by removal, at a first time does not “prime” the charger to activate supply of power at a much later stage as a result only of the control pilot being detected (without checking for plunger movement), since this could occur due to a fault. The first and / or second threshold amount of time may have a value of at least 1, 5, 15 or 30 seconds and / or of at most 60, 30, 15 or 5 seconds. The control system may comprise electronic control circuitry configured to implement some or all of the functions disclosed herein. The control circuitry may comprise analogue circuitry and components and / or digital hardware logic and / or a processor (e.g. a microcontroller) and a memory storing software for execution by the processor. The control system may implement a deterministic finite state machine. It may have a first state, in which the position of the plunger has not yet been detected as being at the first extent (i.e. not yet within a current detection cycle). It may have a second state in which the position of the plunger at the first extent has been detected, but the position of the plunger has not yet been determined to be at the second extent. It may have a third state in which the position of the plunger has been determined to be at the second extent following a detection of the plunger at the first extent. The control system may be configured so that the third state can only be entered from the second state. It may be configured so that the state machine must pass from the first state, through the second state, followed by the third state, in order for the supply of electrical power to be activated. The control system may be configured to prevent the supply of electrical power through the socket in any state other than the third state. Certain conditions may cause the control system to reset to the first state. Such a reset may represent the start of a new detection cycle. In some embodiments, the control system is arranged to return to the first state from the second state if the third state is not reached within a threshold amount of time of reaching the second state. The threshold amount of time may have a value of at least 1, 5, 15 or 30 seconds and / or of at most 60, 30, 15 or 5 seconds. Furthermore, if expected steps or states are detected out of sequence this may also cause the control system to reset to the first state, for example if it is detected that the plug is fully inserted before detecting that the plunger has reached the first extent, this may cause the control system to reset to the first state. The plug may comprise a mating portion that is substantially cylindrical along the insertion axis. It may be substantially circularly cylindrical about the insertion axis. The socket may define a corresponding mating void for receiving the mating portion of the plug. In some embodiments the socket is an IEC 62196 Type 2 socket. In some embodiments the electrical plug is an IEC 62196 Type 2 plug. The plunger is preferably configured to move linearly within the socket, at an angle to the insertion axis, as a result of contact between the plunger and the electrical plug as the electrical plug is inserted into the socket. The angle to the insertion axis may be acute but preferably it is perpendicular (e.g. at 90° to within + / - 0°, 5° or 10°). In some embodiments, the electrical plug comprises a contoured surface, arranged for sliding contact with the plunger so as to move the plunger within the socket as the electrical plug is moved axially within the socket. The electrical plug may have an angled or ramped surface (e.g. at a distal end of the plug) configured to move the plunger away from the plug during at least one phase of an insertion of the plug into the socket. In some embodiments the plunger comprises a ramped face (e.g. a planar face that is inclined relative to the insertion axis of the socket and / or relative to the plunger axis), arranged such that the electrical plug contacts the ramped face of the plunger as the electrical plug is inserted. The ramped face may be at a proximal end of the plunger closest to the plug insertion axis, such that the ramped face contacts the electrical plug as the electrical plug is inserted. This ramp may help the plunger to be more easily and smoothly moved, as a result of contact between the plunger and the electrical plug as the electrical plug is inserted. The ramped face of the plunger may have a corresponding ramp angle (i.e. slope angle) as an angled or ramped surface of the electrical plug, mentioned above, (i.e. so that the two surfaces are substantially parallel) to further improve the smoothness of the motion as these two parts contact, and the plunger is moved outwards by the contact during insertion of the plug. In some embodiments the electrical plug comprises an exterior side surface that is profiled along its length (i.e. parallel to the insertion axis). In some embodiments the second extent corresponds to a position of the plunger when the plunger is in contact with a feature of the profiled surface (e.g. with a base surface of a recess). In some embodiments the plunger is a lock plunger. The lock plunger may be arranged to engage with a feature (e.g. a locking surface) of the profiled surface of the electrical plug, so as to physically lock the electrical plug within the socket. By this it will be understood that the plunger engages with a feature of the profiled surface (e.g. an inner surface of a recess defined in an exterior surface of the plug) such that the electrical plug cannot be removed from the socket by a force along the insertion action until the lock plunger is released from the recess. By “cannot” be removed, it will be understood that it is meant the electrical plug cannot be removed using standard levels of force and standard methodologies for removal. The electrical plug may define a recess (e.g. a well) arranged to receive at least a part of the plunger. The plug may comprise a locking surface. The locking surface may be arranged to lie parallel to the plunger axis. It may be an edge surface of a recess arranged to receive at least a part of the plunger. The recess may be a portion within which an exterior side surface of the plug is closer to the insertion axis than another part of the exterior side surface that is arranged for contact with the plunger. Thus, when the plunger is accommodated within the recess, it will be at a lesser extent away from the insertion axis than when the plunger is contacting another portion of the exterior side surface. A position of the plunger within the recess (e.g. in contact with a base of the recess) may correspond to the second extent. Additionally, or alternatively, the plug may comprise a protrusion. The protrusion may be a portion within which an exterior side surface of the plug extends further from the insertion axis as does another part of the exterior side surface. Thus, when the plunger is located in contact with the protrusion, it will be at a greater extent away from the insertion axis than when the plunger is contacting another portion of the exterior side surface. In some embodiments the first extent corresponds to an extreme of motion of the plunger, i.e. at a maximally outward position from the insertion axis. By this it will be understood that the first extent corresponds to the furthest position to which the plunger is pushed by the electrical plug, as the electrical plug is inserted into the socket under normal usage. In some embodiments, the control system is further arranged to determine that the plunger is at a third extent. The control system may indirectly determine (i.e. infer) that the plunger is at the third extent (e.g. similarly to how it might do so for the second extent), or it may detect directly (e.g. with a contact or position sensor) that the plunger is at the third extent. The third extent may correspond to a position of the plunger when the electrical plug is not present within the electrical socket. The third extent may be the same as or different to the second extent. Having the second extent equal to the third extent may provide for particularly strong locking when using a lock plunger. However, in some embodiments the third extent is less than both the first extent and the second extent. In such embodiments the second extent is less than the first extent, and the third extent is less than the second extent. This allows the position of the electrical plug within the socket to be determined as being one of partially inserted, fully inserted, or fully absent by determining which of the first, second or third extents the plunger is at. This may help enhance safety. In some embodiments, the distance between the first extent and the third extent may be approximately double the distance between the first extent and the second extent. In other words, the second extent may be approximately halfway (i.e. equidistant) between the first extent and the third extent. This may improve the ease and / or accuracy of detection of the plunger position (i.e. of distinguishing between the three positions), while still providing acceptable locking strength in embodiments that have a locking plunger. In some embodiments the electric vehicle supply apparatus may further comprise a biasing mechanism arranged to bias the plunger or lock plunger towards the insertion axis. As a result, absent any other forces on the plunger (for example a radial push, away from the insertion axis, provided by the electrical plug as it is inserted), the plunger will move towards the insertion axis, as far as it is able to move in that direction. Where no electrical plug is inserted into the socket, the plunger may be biased to a position at the third extent. Where an electrical plug is fully inserted within the socket, the plunger may be biased to a position at the second extent, e.g. in contact with a recessed surface of the plug. This is particularly beneficial where the plunger is a lock plunger since it means that it may be biased into a position of being maximally-inserted in the recess, e.g. engaging so as to lock the electrical plug in place so that the engagement of the locking plunger with a locking surface of the plug is improved. The biasing mechanism may be an active mechanism, for example comprising a solenoid, (i.e. requiring an active supply of power), but preferably the biasing mechanism is passive. For example, the biasing mechanism may comprise a spring, such as a coil spring. A passive mechanism can reduce power consumption demands and may be especially advantageous where the plunger is a locking plunger, as the locking effect can be maintained without requiring power to be supplied to the biasing mechanism, thereby improving safety. In some embodiments, the electric vehicle supply apparatus further comprises an actuator mechanism, arranged to actuate movement of the plunger away from the insertion axis. This is particularly advantageous where the plunger is biased towards the insertion axis, as the actuator mechanism may allow the force of the biasing mechanism to be overcome, so that the plunger can be moved away from the insertion axis, against the force of the biasing mechanism. In embodiments in which the plunger is a lock plunger, this allows the lock plunger to be removed from a recess (i.e. unlocked), allowing removal of the electrical plug from the socket. The actuator mechanism may comprise a solenoid. The electric vehicle supply apparatus may further comprise an integral power supply (e.g. a battery) arranged to supply electrical power to the actuator mechanism. This helps to ensure that the lock plunger can be disengaged even where a main power supply to the electric vehicle supply apparatus fails. Additionally, or alternatively, the actuator mechanism may comprise a manually actuated mechanism (i.e. a mechanism such as a handle that is actuated by a user, to manually move the plunger away from the insertion axis); this may be useful in case of a main power-supply failure. In some embodiments the electric vehicle supply apparatus may comprise a plurality of plungers, wherein each plunger is arranged as disclosed herein. The plungers may be positioned at different circumferential positions around the socket. Likewise, the electrical plug may comprise a plurality of recesses, each corresponding to a respective plunger and arranged to receive the respective plunger. The control system may be configured to activate a supply of electrical power through the socket only once all of the plurality of plungers are at their respective second extents after having previously reached their respective first extents. The EV supply apparatus may comprise an electrical interface for receiving electrical power into the supply apparatus—e.g. from the mains supply of a building. It may comprise circuitry for further controlling the supply of power through the socket—e.g. for controlling the voltage and / or current and / or duration of supply. It may comprise circuitry for sending and / or receiving control signals through the socket. Features of any aspect or embodiment described herein may, wherever appropriate, be applied to any other aspect or embodiment described herein. Where reference is made to different embodiments or sets of embodiments, it should be understood that these are not necessarily distinct but may overlap. BRIEF DESCRIPTION OF THE DRAWINGS Certain preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figures 1-6 are partially-schematic cross-sectional views showing various stages of a process in which an electrical plug is inserted into a socket of an electric vehicle supply apparatus according to a first embodiment of the present invention; Figure 7 is a cutaway view of the plug and socket of Figures 1-6, showing inner details of the plug; Figure 8 is a cross-sectional view of the plug and socket of Figure 7, looking along the line A in Figure 7; Figure 9 is a flow diagram representing the flow that must be followed in order for power supply to be activated, and the states which the control system passes through in this process, according to the first embodiment of the invention; Figure 10 is a cross-sectional view showing an electrical plug partially inserted into a socket of an electric vehicle supply apparatus according to a second embodiment of the present invention; and Figure 11 is a flow diagram representing the flow that must be followed in order for power supply to be activated, and the states which the control system passes through in this process, according to the second embodiment of the invention. DETAILED DESCRIPTION Figure 1 shows an electric vehicle supply system 1, including an electric vehicle supply apparatus (in the form of an untethered EV charger) 2, and an electrical plug 6 which is coupled to an EV charging cable 3. The EV charger 2 includes a socket 4, mounted in a housing 5 of the supply apparatus 2. The socket 4 is configured to receive the electrical plug 6 along an insertion axis 8. The electric vehicle charger 2 contains a plunger mechanism 10, mounted to a wall of the socket 4 inside the charger. The plunger mechanism 10 contains a plunger 15 that is arranged to move linearly along a plunger axis, perpendicular to the insertion axis 8, towards and away from the insertion axis 8. It is biased by a coil spring 12 towards the insertion axis 8. The biasing force of the spring 12 can be overcome as a result of contact between the plunger 15 and the electrical plug 6. In particular, the plunger 15 includes a ramped surface 16 at a distal end of the plunger 15. The ramped surface 16 can contact a ramped edge surface 18 of the electrical plug 6, such that the two surfaces 16, 18 slide relative to each other and in doing so the plunger 15 is pushed outward from the insertion axis 8 as the electrical plug 6 is inserted into the socket 4 along the insertion axis 8. In addition to being moved as a result of insertion of the electrical plug 6, the biasing force of this spring 12 can also be overcome by an actuation force supplied by a solenoid 14, in order to move the plunger 15 away from the insertion axis 8 (i.e. out of the socket cavity). The solenoid 14 is part of the plunger mechanism 10 and includes a magnetic plunger 14a, a housing 14b and electromagnetic windings 14c. When the solenoid windings 14c are energised, the resulting magnetic field causes the magnetic plunger 14a, which is rigidly attached to the plunger 15, to move away from the insertion axis 8. In this example the plunger 135 is a lock plunger, i.e. it also has the function of locking or holding the electrical plug 6 in place within the socket 4 for a period of time after insertion of the electrical plug 6. The electrical plug 6 has an exterior side surface 20 that is profiled, i.e. that varies in radial extent along the insertion axis. In this example, the exterior side surface 20 includes a recess 22 in the form of a well. When the electrical plug 2 is fully inserted within the socket 4, as seen in Figure 5, the plunger 15 engages with a locking edge of the recess 22 (the edge closer to the distal end of the electrical plug 2), physically locking the electrical plug 6 within the socket 4 until the plunger 15 is moved away from the insertion axis 8 sufficiently far to be outside of the recess 22. The electrical vehicle charger 2 further includes a control system (represented schematically in Figure 1) that comprises control circuitry 24, a proximity sensor 26, and an insertion-detection sensor 28. This control system comprises electronic components and circuitry configured to detect when the plunger 15 reaches a first extent, outward from the insertion axis 8, indicative of the electrical plug 6 being partially inserted within the socket 4. In particular, the control system comprises a proximity sensor 26, which is arranged to detect when a particular part or reference feature 30 of the plunger 15 (e.g. a magnet, an optical reflector, a protrusion, or a conductive contact) is within a predetermined proximity of the sensor 26, indicative of the plunger 15 being at an extreme of its motion (i.e. its furthest position from the insertion axis 8, referred to herein as the first extent - seen in Figure 4). The proximity sensor 26 may detect proximity using optical, capacitative, magnetic, mechanical or electrical-contact sensing, or by any other appropriate means. The proximity sensor 26 in this example outputs a proximity status signal to the control circuitry 24 over a signal line represented by the dashed line connecting the control circuitry 24 and the proximity sensor 26. The control circuitry 24 is also arranged to determine that the plunger 15 is at a second extent (seen in Figure 5), outward from the insertion axis 8. The second extent is the extent that the plunger 15 is at when the electrical plug 6 is fully inserted into the socket 4. In this example the second extent is the same as the third extent (seen in Figure 1) that the plunger 15 is at when no plug is inserted even partially within the socket 4. In this example, the control system does not directly detect the position of the plunger 15 at the second extent (and indeed this would not be sufficient to determine full insertion of the electrical plug 6), but rather determines it implicitly based on other received signals. In particular, the control circuitry 24 in this embodiment is connected to an insertion detection sensor 28 which is arranged to detect when the electrical plug 6 is fully inserted within the socket 4, and from this to infer that the plunger 15 must be at the second extent. In this example, the insertion detection sensor 28 is an electrical contact sensor, the operation of which is described in greater detail below with reference to Figures 7 and 8. The insertion detection sensor 28 in this example outputs signals to the control circuitry 24, as represented by the dashed line connecting the control circuitry 24 and the insertion detection sensor 28. The electrical vehicle supply apparatus 1 is arranged to activate a supply of electrical power through the socket 4 based on the state and timing of signals received by the control circuitry 24; in particular the control system is arranged to activate a supply of electrical power to a vehicle, such as a car, only when the plunger 15 is at the second extent after having previously reached the first extent. This supply of power may be controlled by one or more switches or relays within the EV charger 2. Successive stages of insertion of the electrical plug 6 into the socket 4 are shown in Figures 1-6, and are described in greater detail below with reference to these Figures and also in relation to the flow chart of Figure 9. To initiate insertion of the electrical plug 6 into the socket 4, a pushing force is applied to the electrical plug 6, along the direction of the arrow 32, causing it to move into the socket 4, along the insertion axis 8. Before the electrical plug 2 contacts the plunger 15, the plunger 15 is at the position referred to herein as the “third extent” outward from the insertion axis 8, as seen in Figure 1. Referring to Figure 9, at this point in time, the process is at stage 100, and the control system is in the first state 200. As shown in Figure 2, once the electrical plug 6 has been inserted a sufficient distance into the socket 4, the ramped surface 16 of the plunger 15 contacts the ramped edge surface 18 of the electrical plug 6, as shown in Figure 2. Then as the electrical plug 6 is pushed further the two surfaces slide relative to each other and in doing so the plunger 15 is pushed outwards, away from the insertion axis 8, as seen in Figure 3. This compresses the spring 12. This movement continues until the plunger 15 is pushed to the furthest outward position of its motion, the first extent, shown in Figure 4. This is the point of maximum compression for the spring 12. In this position the proximity sensor 26 detects that it is in proximity with the reference feature 30 of the plunger 15, and therefore detects that the plunger 15 is at the first extent. This is relayed to the control circuitry 24. As represented at stage 102 of the flowchart of Figure 9, this affirmative check that the plunger 15 is at the first extent causes the control system to transition to a second state 202. Next, the electrical plug 6 is inserted further into the socket 4 until it is in the fully inserted position within the socket 4, as shown in Figure 5. In this position, the plunger 15 is pushed towards the insertion axis by the spring 12 as it decompresses, such that a distal portion of the plunger 15 is accommodated within the recess 22. This locks the electrical plug 6 within the socket 4 as described above, until the lock is released by the solenoid 14, as also described above. Figure 6 shows the position of the plunger 15 when the solenoid 14 has been activated to move the plunger 15 out of the recess 29. Referring again to Figure 9, once the plunger 15 is detected at the first extent (as shown in Figure 4), and the control system transitions to the second state 202, it must be determined that, within a predetermined cumulative threshold amount of time (Time-out 1 + Time-out 2), the plunger 15 has moved to the second extent in order to reach the third state 204, in which supply of electrical power through the socket 4 is activated. This determination is carried out by making two steps, 104, 106, each of which must take place within a respective threshold amount of time (Time-out 1, Time- out 2), otherwise the control system times out and returns to the first state 200, from which the process must begin again. In the first stage 104, it is checked whether the plunger 15 has moved away from the first extent, i.e. itis no longer detected by the proximity sensor 26. It is important that this check is made since if the plunger 15 stays at the first extent, despite electrical contact with the plug being detected (so that the check at stage 106 would be affirmative) this is indicative that either the plug has not quite been fully inserted (far enough for the plunger 15 to move inward into the recess) or the locking action of the plunger 15 has failed to engage. This could happen for example where the spring 12 is mechanically damaged or there is an obstruction to its motion, for example debris. The check at stage 104 therefore helps to ensure full insertion of the electrical plug 6 and also to check that the locking action of the plunger 15 is successfully engaged. This must occur within a threshold amount of time, referred to as Time-out 1, otherwise the control system resets to the state 200. If this is confirmed, then it is checked, at stage 106, whether contact of a control pilot connector 70 with a control pilot pin 72 is detected, based on a change of state being detected in relation to the control pilot pin 72. This check process 106 is described below with reference to Figure 7 and 8. If this check is negative, for the threshold amount of time Time-out 2, this is indicative that the electrical plug 8 was partially inserted within the socket 4 (pushing the plunger 15 out to its second extent), but was then removed, or at least never fully inserted, and thus the control system does not activate the supply of power, but instead resets to the first state 100. Time-out 2 may have a length of 5 minutes, to allow a user more time to fully plug in their electric vehicle. This is particularly important where the process of connecting the electric vehicle also requires a separate plug (on the other end of the charging cable) to be inserted into the electric vehicle, since this will take the user more time, and will need to have been done before the change in voltage referred to below will be detected, signalling the end of step 106. Turning to Figure 7, a cross-section of the electrical plug 6 and the socket 4 of Figures 1-6 is shown. Figure 8 shows a cross-sectional view of the electrical plug 6 and the socket 4 along the line A of Figure 7. The socket 4’ defines a cavity 74, within which there are arranged protrusions 76, protruding out from an interior end surface 78 of the socket 4. The electrical plug 6 has cavity portions 82 defined within the insertable portion 80 of the plug 6. The cavity 74 of the socket is arranged to receive the insertable portion 80 of the electrical plug 6, and the cavity portions 82 of the electrical plug 6 are arranged to receive the protrusions 76 of the socket 4. In this way the electrical plug 6 is fully inserted within the socket 4. Each of the cavity portions 82 of the electrical plug 6 contains a respective electrical pin for signalling and / or power transmission. In particular, one of the cavity portions 82 of the electrical plug 6 (the lower one from the view of Figure 8) contains a pin referred to as the control pilot pin 72. The protrusions 76 of the socket comprise channels 84, arranged to receive these pins. In particular, one protrusion 76 (the lower one from the view of Figure 8) comprises a channel referred to as a control pilot connector 70. The insertion detection sensor 28 is arranged to detect when the control pilot connector 70 contacts the control pilot pin 72, and thus to detect full insertion of the electrical plug 6 into the socket 4. For example, the insertion detection sensor 28 may comprise or be connected to a contact sensor that is arranged to detect contact between a distal end portion of the electrical plug (a protrusion, e.g. the control pilot pin) and an interior end portion of the socket (a channel, e.g. the control pilot connector), and thereby to detect that the electrical plug is fully inserted within the socket. This detection may be carried out by detecting a change in voltage at the control pilot connector 70 that arises as a result of its electrical connection to the control pilot pin 72. Figure 10 is a cross-sectional view showing an electrical plug 6’ partially inserted into a socket 4’ of an electric vehicle supply apparatus 2’ according to a second embodiment of the present invention. It has many similarities to the system 1 of Figure 1, and like components have been indicated with the same reference numerals but followed by an apostrophe. Only those components that differ from the embodiment of Figures 1-8 will be described in detail herein. The electric vehicle supply apparatus 2’ comprises a control system that differs from the control system of the first embodiment. In particular, the control system does not include a proximity sensor, or an insertion detection sensor, but instead includes a position sensor 27’ that is communicatively coupled to the control circuitry 25’. The position sensor 27’ is arranged to determine the position of the plunger 15’, i.e. to detect the particular radial extent that the plunger 15’ is located at, rather than simply detecting it as being either present or absent from one specific location (as is done by a proximity sensor using the reference feature 30). The position sensor 27’ may detect the position of the plunger 15’ by detecting the distance from the position sensor 27’ to a part of the plunger 15’ (i.e. the distance between them). The other difference compared to the first embodiment is that the plunger 15’ extends further into the socket 4’ than the plunger 15, i.e. when the plunger 15’ is in a “neutral position”, acted on only by the force of the spring 12’, and not contacting the electrical plug 2, it extends further towards the insertion axis 8’ than in the first embodiment. This position is referred to as the “third extent”. It will therefore be appreciated that the third extent is the position of the plunger 15’, relative to the insertion axis 8, when the electrical plug 6’ is not inserted sufficiently far into the socket 4’ to contact the plunger 15". It will be appreciated that in this embodiment, not only are the first extent (the outer extreme position of the plunger 15’) and the second extent (the position of the plunger 15’ on the recess 22’) different from each other, but they are also both different to the third extent. Thus, in this example, determining that the plunger 15’ is at the second extent is determinative of the electrical plug 6’ being fully inserted into the socket 4’, since the plunger 15’ can only reach this extent (and remain there stationary) when it is located in the recess 22". When the plunger 15’ is not accommodated in the recess 22’ it will be moved by the spring 12’ back to the third extent, which is closer to the insertion axis 8’. In other words, the third extent (reached when electrical plug 6’ is not sufficiently far within the socket 4’ to contact the ramped face 16’ of the plunger 15’) is smaller (i.e. closer to the insertion axis 8) than the second extent (reached when the plunger 15’ is accommodated within the recess 22’. Thus, in this embodiment, it is not necessary to separately detect full insertion of the plug 8’ into the socket 4’ (i.e. with a control-pilot insertion detection sensor) in order to establish that the supply of power can be safely activated. Instead, it can just be detected that the plunger 15' is located at the second extent (after having passed through the first extent). Nevertheless, electrical-contact sensing may still be implemented in this embodiment to provide additional confidence. Figure 11 is a flow diagram representing this alternative method. The process starts at stage 100", at which point the control system is in a first state 200’. The control system monitors for the plunger 15’ reaching the first extent (i.e. the furthest outward position it is arranged to reach) at which point the stage 102’ is passed, and the control system switches to being in state 202’. Next, the at stage 104’, instead of checking separately that the plunger has moved away from the first extent, and then independently checking for full insertion, the control circuitry 25’ simply uses the position sensor 27 to detect that the plunger is at the second extent (i.e. located within the recess 22’ of the exterior side surface 20’). This check indicated that the electrical plug 6’ has been fully inserted in the socket 4' and also that the plunger 15’ is successfully locking the electrical plug 6’ into the socket 4', so it is sufficient to move the control system into the third state 204’, in which supply of power through the socket 4’ is activated. It is noted that the plunger 15° must reach the second extent within a threshold amount of time of reaching the first extent, otherwise the control system will “time-out” and reset back from the second state 202 to the first state 200’ to begin the process again. The check at stage 104’ may also require the plunger 15’ to remain at the second extent for at least a threshold amount of time, e.g. to ensure that transition to the third state 204’ is not triggered just by the plunger 15’ passing through the second extent as it moves inwards or outwards. In a variant set of embodiments there may be two, three, four or more plunger mechanisms mounted to a wall of the socket inside the charger, each of identical or similar design to the plunger mechanism 10, and a corresponding plurality of recesses, each of identical or similar design to the recess 22. These may be arranged at different circumferential positions — e.g. with two plungers on opposite sides. The control system may activate the supply of electrical power only when every plunger is at its second extent after having previously reached its first extent. It will be appreciated by those skilled in the art that the invention has been illustrated by describing one or more specific embodiments thereof, but is not limited to these embodiments; many variations and modifications are possible, within the scope of the accompanying claims.

Claims

Claims 1. An electric vehicle supply apparatus, comprising: a socket for receiving an electrical plug along an insertion axis; a plunger, configured to move within the socket, at an angle to the insertion axis, as a result of contact between the plunger and the electrical plug as the electrical plug is inserted into the socket; and a control system configured to: detect when the plunger reaches a first extent, outward from the insertion axis, indicative of the electrical plug being partially inserted within the socket: determine that the plunger is at a second extent, outward from the insertion axis, wherein the second extent is less than the first extent, and wherein the second extent is such that, when the electrical plug is fully inserted into the socket, the plunger is at the second extent; and activate a supply of electrical power through the socket only when the plunger is at the second extent after having previously reached the first extent.

2. The electric vehicle supply apparatus of claim 1, wherein the control system comprises an insertion detection sensor, independent of the plunger, for determining that the electrical plug is fully inserted within the socket, and wherein the electric vehicle supply apparatus is configured to activate the supply of electrical power through the socket only when both conditions are met that: i) the plunger is at the second extent after having previously reached the first extent: and ii) the control system has detected, using the insertion detection sensor, that the electrical plug is fully inserted within the socket.

3. The electric vehicle supply apparatus of claim 2, wherein the insertion detection sensor comprises an optical sensor, a capacitative sensor, a magnetic sensor, or a mechanical switch.

4. The electric vehicle supply apparatus of claim 2, wherein the insertion detection sensor comprises a contact sensor, arranged to detect contact between a first portion of the electrical plug and a first portion of the socket, indicative of the electrical plug being fully inserted within the socket.

3. The electric vehicle supply apparatus of claim 4, wherein the contact sensor is configured to detect contact by detecting a change in voltage resulting from contact between an electrical pin of the electrical plug and an electrical connector of the socket.

6. The electric vehicle supply apparatus of any preceding claim, wherein the control system further comprises a proximity sensor, arranged to detect when the plunger is at the first extent.

7. The electric vehicle supply apparatus of any preceding claim, wherein the plunger being at the second extent is determinative of the plug being fully inserted.

8. The electric vehicle supply apparatus of claim 7, wherein the control system comprises a position sensor, arranged to determine a distance of the plunger along its direction of movement, wherein the position sensor is arranged to detect when the position of the plunger corresponds to the second extent, and thereby to detect that the electrical plug is fully inserted within the socket.

9. The electric vehicle supply apparatus of any preceding claim, wherein the electric vehicle supply apparatus is configured to activate a supply of electrical power through the socket only when the plunger is at the second extent at a second time after having previously reached the first extent at a first time, wherein the time between the first time and the second time is lower than a threshold amount of time.

10. The electric vehicle supply apparatus of any preceding claim, wherein the socket is an IEC 62196 Type 2 socket.

1. The electric vehicle supply apparatus of any preceding claim, wherein: the plunger is a lock plunger; the electrical plug comprises an exterior side surface that is profiled along its length; and the lock plunger is arranged to engage with a feature of the profiled surface of the electrical plug, so as to physically lock the electrical plug within the socket.

12. The electric vehicle supply apparatus of any preceding claim, wherein the electric vehicle supply apparatus furthers comprise a biasing mechanism, arranged to bias the plunger towards the insertion axis.

13. The electric vehicle supply apparatus of any preceding claim, wherein the plunger comprises a ramped face, arranged such that the electrical plug contacts the ramped face of the plunger as the electrical plug is inserted.

14. The electric vehicle supply apparatus of any preceding claim, wherein the first extent corresponds to an extreme of motion of the plunger, at a maximally outward position from the insertion axis.

18. The electric vehicle supply apparatus of any preceding claim, wherein the electrical plug comprises an exterior side surface that is profiled along its length and wherein the second extent corresponds to a position of the plunger when the plunger is in contact with a feature of the profiled surface.

16. The electric vehicle supply apparatus of any preceding claim, wherein the control system is further arranged to determine that the plunger is at a third extent, wherein the third extent corresponds to a position of the plunger when the electrical plug is not present within the electrical socket.

17. The electric vehicle supply apparatus of any preceding claim, further comprising an actuator mechanism, arranged to actuate movement of the plunger away from the insertion axis.

18. An electric vehicle supply system, comprising: the electrical vehicle supply apparatus as claimed in any preceding claim; and an electrical plug for insertion in the socket of the electrical vehicle supply apparatus.

19. The electric vehicle supply system of claim 18, wherein the electrical plug is coupled to a charging cable for supplying electrical power to an electric vehicle.

20. The electric vehicle supply system of claim 18 or 19, wherein the electrical plug defines a recess arranged to receive at least a part of the plunger.

21. The electric vehicle supply system of any of claims 18 to 20, wherein the electrical plug is an IEC 62196 Type 2 plug. Claims 9. An electric vehicle supply apparatus, wherein the electric vehicle supply apparatus is an untethered electric vehicle charger, the electric vehicle supply apparatus comprising: a socket for receiving an electrical plug along an insertion axis; a plunger, configured to move within the socket, at an angle to the insertion axis, as a result of contact between the plunger and the electrical plug as the electrical plug is inserted into the socket; and a control system configured to: detect when the plunger reaches a first extent, outward from the insertion axis, indicative of the electrical plug being partially inserted within the socket: determine that the plunger is at a second extent, outward from the insertion axis, wherein the second extent is less than the first extent, and wherein the second extent is such that, when the electrical plug is fully inserted into the socket, the plunger is at the second extent; and activate a supply of electrical power through the socket only when the plunger is at the second extent after having previously reached the first extent; wherein the electric vehicle supply apparatus is configured to activate a supply of electrical power through the socket only when the plunger is at the second extent at a second time after having previously reached the first extent at a first time, wherein the time between the first time and the second time is lower than a threshold amount of time, and wherein the threshold amount of time has a value of at least 5 minutes.

2. The electric vehicle supply apparatus of claim 1, wherein the control system comprises an insertion detection sensor, independent of the plunger, for determining that the electrical plug is fully inserted within the socket, and wherein the electric vehicle supply apparatus is configured to activate the supply of electrical power through the socket only when both conditions are met that: i) the plunger is at the second extent after having previously reached the first extent: and ii) the control system has detected, using the insertion detection sensor, that the electrical plug is fully inserted within the socket.

3. The electric vehicle supply apparatus of claim 2, wherein the insertion detection sensor comprises an optical sensor, a capacitative sensor, a magnetic sensor, or a mechanical switch.

4. The electric vehicle supply apparatus of claim 2, wherein the insertion detection sensor comprises a contact sensor, arranged to detect contact between a first portion of the electrical plug and a first portion of the socket, indicative of the electrical plug being fully inserted within the socket.

5. The electric vehicle supply apparatus of claim 4, wherein the contact sensor is configured to detect contact by detecting a change in voltage resulting from contact between an electrical pin of the electrical plug and an electrical connector of the socket.

6. The electric vehicle supply apparatus of any preceding claim, wherein the control system further comprises a proximity sensor, arranged to detect when the plunger is at the first extent. f. The electric vehicle supply apparatus of any preceding claim, wherein the plunger being at the second extent is determinative of the plug being fully inserted.

8. The electric vehicle supply apparatus of claim 7, wherein the control system comprises a position sensor, arranged to determine a distance of the plunger along its direction of movement, wherein the position sensor is arranged to detect when the position of the plunger corresponds to the second extent, and thereby to detect that the electrical plug is fully inserted within the socket.

9. The electric vehicle supply apparatus of any preceding claim, wherein the socket is an IEC 62196 Type 2 socket.

10. The electric vehicle supply apparatus of any preceding claim, wherein: the plunger is a lock plunger; the electrical plug comprises an exterior side surface that is profiled along its length; and the lock plunger is arranged to engage with a feature of the profiled surface of the electrical plug, so as to physically lock the electrical plug within the socket.

11. The electric vehicle supply apparatus of any preceding claim, wherein the electric vehicle supply apparatus furthers comprise a biasing mechanism, arranged to bias the plunger towards the insertion axis.

12. The electric vehicle supply apparatus of any preceding claim, wherein the plunger comprises a ramped face, arranged such that the electrical plug contacts the ramped face of the plunger as the electrical plug is inserted.

13. The electric vehicle supply apparatus of any preceding claim, wherein the first extent corresponds to an extreme of motion of the plunger, at a maximally outward position from the insertion axis.

14. The electric vehicle supply apparatus of any preceding claim, wherein the electrical plug comprises an exterior side surface that is profiled along its length and wherein the second extent corresponds to a position of the plunger when the plunger is in contact with a feature of the profiled surface.

15. The electric vehicle supply apparatus of any preceding claim, wherein the control system is further arranged to determine that the plunger is at a third extent, wherein the third extent corresponds to a position of the plunger when the electrical plug is not present within the electrical socket.

16. The electric vehicle supply apparatus of any preceding claim, further comprising an actuator mechanism, arranged to actuate movement of the plunger away from the insertion axis.

17. An electric vehicle supply system, comprising: the electrical vehicle supply apparatus as claimed in any preceding claim; and an electrical plug for insertion in the socket of the electrical vehicle supply apparatus.

18. The electric vehicle supply system of claim 17, wherein the electrical plug is coupled to a charging cable for supplying electrical power to an electric vehicle.

19. The electric vehicle supply system of claim 17 or 18, wherein the electrical plug defines a recess arranged to receive at least a part of the plunger.

20. The electric vehicle supply system of any of claims 17 to 19, wherein the electrical plug is an IEC 62196 Type 2 plug.

Images