Switching assembly

Abstract

A mechanical electronic switching assembly for a multi -phase motor comprises a fixed body comprising a plurality of fixed contacts each arranged to be permanently connected to a corresponding terminal of a corresponding phase fraction; a moveable body that can be moved with respect to the fixed body between a first position, in which the phases are arranged in a first electrical configuration; and a second position, in which the phases are arranged in a second electrical configuration, wherein the second electrical configuration is different from the first electrical configuration, and an actuator arranged to move the at least one moveable body between the first position and the second position. The movable body comprises a plurality of movable contacts each arranged to contact at least one of the fixed contacts. The movable body and the fixed body together are arranged to provide two different current flow paths such that the electrical configuration of phase fraction terminals can be reconfigured between the first electrical configuration and the second electrical configuration by selecting the corresponding current flow path, the current flow path varying in both the movable body and the fixed body between the first electrical configuration and the second electrical configuration.

Description

[0001] SWITCHING ASSEMBLY

[0002] The invention relates to an electro-mechanical switching assembly arranged to allow a configuration of motor windings of a motor to be changed, for example from a series configuration to a parallel configuration, and in particular to circuit designs and physical implementations that allows for such an electro-mechanical switching assembly to be made more compact.

[0003] Motor windings generally take the form of coils of conductive wires wrapped around a magnetic core. The windings provide a path for current to flow to create a magnetic field so as to spin a rotor of the motor. Motor windings can take many forms, although three-phase windings with two coils (or “phase fractions”) per phase are the most commonly used in alternating current (AC) motors for industrial applications. Motor winding configuration influences parameters such as the operating speed, torque, and power output of the motor. Selecting a suitable winding configuration for a motor allows its performance to be optimised for a given purpose. For example, in a series configuration, the two (or more) coils of each phase are connected in series. In a parallel configuration, the two (or more) coils of each phase are connected in parallel. At low speeds, a series configuration is generally selected to achieve a relatively high torque output. At higher speeds, a parallel configuration is generally selected to achieve a higher power.

[0004] Other winding configurations with differing properties - e.g. delta and star configurations - are also known and may be chosen between. For example, a star configuration may be preferable for lower speed / lower power operation, and a delta configuration may be preferred for higher-speed / higher power operation. A star configuration, “Y”, can be obtained by joining together similar ends of windings (i.e. all “starting” ends of windings or all “finishing” ends of windings) at a common point, generally referred to as the Neutral Point, or Star Point (so forming a Y shape when there are three phases present, plus a neutral wire, for a total of four wires). The other ends of each coil are joined to the line wires. This configuration (particularly, of three phases) is often used in power distribution, transformers and small scale domestic and residential applications. By contrast, a Delta configuration, “A”, is obtained by connecting the starting end of the first winding to the finishing end of the second winding and so on (for all three windings, in a three-phase system) which forms a closed loop. This configuration (particularly, of three phases) is commonly used in power transmission, transformers, and large scale industrial and commercial applications. No neutral wire is needed in this configuration.

[0005] The principle of reconfiguring windings of a given motor in different stages of its use has been a topic of some published research, and has been applied commercially in some limited applications, but is not yet in general use - at least in part due to the switches being generally complex and cumbersome. Currently, switches for motor windings are generally either bulky and cumbersome, and / or very expensive (for example using complex and delicate semiconductor switches). The smaller assemblies generally use semiconductor switches rather than mechanical switches - this reduces the number of moving parts (so allowing the assembly to be smaller), but makes the assemblies much more expensive. The invention as disclosed herein aims to provide an elegant mechanical solution that can provide a more compact switching solution without resorting to use of semiconductor switches.

[0006] WO 2020 / 194230 (Al), and US 2022 / 190691 (Al), its corresponding application in the United States, discloses a switching device for an electric motor having a plurality of phases, the switching device comprising a fixed with a plurality of connection portions and at least one moveable body that can be rotated with respect to the fixed body between at least a first position, in which the phases are arranged in a first electrical configuration, and a second position, in which the phases are arranged in a second electrical configuration which is different from the first electrical configuration.

[0007] According to a first aspect of the invention, there is provided a mechanical electronic switching assembly for an electric motor, said motor being a multi-phase motor comprising a winding for each phase, the windings being arranged such that each phase comprises a number of phase fractions, each phase fraction extending between a pair of terminals, the mechanical electronic switching assembly comprising: a fixed body comprising a plurality of fixed contacts each arranged to be permanently connected to a corresponding terminal of a corresponding phase fraction; at least one moveable body that can be moved with respect to the fixed body between: a first position, in which the phases are arranged in a first electrical configuration; and a second position, in which the phases are arranged in a second electrical configuration, wherein the second electrical configuration is different from the first electrical configuration, wherein the at least one movable body comprises a plurality of movable contacts each arranged to contact at least one of the fixed contacts of the fixed body in at least one of the first configuration and the second configuration, and wherein the at least one movable body and the fixed body together are arranged to provide two different current flow paths such that the electrical configuration of phase fraction terminals can be reconfigured between the first electrical configuration and the second electrical configuration by selecting the corresponding current flow path, and wherein each current flow path has a portion provided by the movable body and a portion provided by the fixed body, and wherein both portions of the current flow path vary between the first electrical configuration and the second electrical configuration; and an actuator arranged to move the at least one moveable body between the first position and the second position.

[0008] Unlike for the switching device of WO 2020 / 194230 (Al), in which all stationary contacts are used in both positions such that the current flow path within the fixed body is the same, according to this aspect of the invention the current flow path in each of (i) the at least one movable body, and (ii) the fixed body is different between the first electrical configuration and the second electrical configuration. This use of different routes within both bodies may increase flexibility and allow the same switching operation to be provided with fewer contacts and / or a more physically resilient (longer-lasting) and / or easy to manufacture design, optionally not relying on rotational movement for making and breaking contacts.

[0009] There may be at least as many fixed contacts as there are phase fraction terminals. In embodiments in which each phase has just a single phase fraction / a single coil (and therefore just two terminals), there may be three fixed contacts.

[0010] Such switching assemblies may be more compact than current assemblies, and potentially also much lower cost in mass manufacture. For example, a total volume of the switching assembly including an actuation mechanism for moving the movable body may be around 1500 cm3, and the switching assembly may have a maximum dimension of no more than 15 cm, and optionally of no more than 14 cm, 13 cm, 12 cm, 11 cm, or 10 cm. The switching assembly may have a minimum dimension, e.g. depth, of no more than 8 cm, and optionally of no more than 5 cm, 3 cm, or 2.5 cm.

[0011] The first and second electrical configurations may be: (i) series and parallel; or (ii) star and delta. The number of phase fractions may be just one for at least one phase, and optionally for all phases - it will be appreciated that series-parallel switching only applies when at least one phase has multiple phase fractions, however. Star-delta switching may be implemented irrespective of the number of phase fractions per phase.

[0012] The at least one moveable body may be arranged to be moved with respect to the fixed body so as to move the phases between more than two different electrical configurations; for example between four different configurations. There may be a plurality of movable bodies. A single movable body may comprise two (or more) different current paths - a first path only may be used in the first configuration and a second path only may be used in the first configuration, or a particular one or more of the current paths may be used in two or more different configurations, e.g. with the movable body being realigned so as to contact a different pair of stationary contacts with a given pair of movable contacts. In some implementations, a given fixed contact may make contact with a different movable contact of the same movable body in different configurations. In some implementations, a given fixed contact may make contact with a movable contact in a different movable body in different configurations, such that the same fixed contact connects to a current flow path through a different movable body, depending on the configuration. Similarly, the current flow path in the first movable body may connect with a different fixed contact in different configurations, so being in use in multiple configurations. Unlike in prior art switching devices in which a pair of movable contacts of a movable body may simply make and break contact with the same matched pair of fixed contacts, the current paths can therefore be multi-purpose by varying which contacts they connect to, so providing improved design efficiency. Especially in embodiments with more than two different configurations, the mechanical electronic switching assembly may comprise two (or more) separably-moveable movable bodies each arranged to be moved with respect to the fixed body between a first position and a second position so as to move the phases between two different electrical configurations. Different combinations of positions of the movable bodies may therefore provide more than two different electrical configurations. For example, a switching assembly may comprise two separably-moveable movable bodies each arranged to be moved with respect to the fixed body between a first position and a second position so as to move the phases between two different electrical configurations, so as to provide four different electrical configurations. The total number of electrical configurations may be four. Alternatively, one or more additional configurations (e.g. a neutral / off configuration with all circuits broken) may be provided.

[0013] At least one of the fixed contacts may be arranged to be unused in one of the first electrical configuration and the second electrical configuration. Here, being “unused” in a given configuration means that the fixed contact does not form part of a path along which current flows in that configuration. At least one fixed contact many therefore be arranged to form part of the current flow path in only one of the first electrical configuration and the second electrical configuration. Similarly, at least one movable contact may be arranged to form part of the current flow path in only one of the first electrical configuration and the second electrical configuration.

[0014] The total number of different conductive pathways within the single movable body, or within all movable bodies in implementations with multiple movable bodies, may be less than twice the number of phase fractions (i.e. may be a maximum of (2n-l), where n is equal to the number of phase fractions). The at least one movable body may comprise a total of no more than (2n-l) movable contacts, and optionally may have exactly (2n-l) movable contacts, where n is equal to the number of phase fractions.

[0015] The total number of different conductive pathways may be less than twice the number of phase fractions.

[0016] The total number of fixed contacts may be equal to the total number of phase fraction terminals. The number of contacts and / or of conductive pathways (current paths) may be lower than for prior art designs offering the same switching capability for the same number of phases and phase fractions.

[0017] The actuator may be arranged to not be continuously powered - the actuator may be powered only during the process of switching the configurations, and may be powered off / inactive between uses. The actuator therefore may not act as a locking mechanism to hold them movable body in each position, and optionally no such locking mechanism may be provided. The actuator may be powered only when moving the movable body. On various implementations, no locking mechanism may be provided to lock the movable body in the first or second position.

[0018] The mechanical electronic switching assembly may comprise a single actuator arranged to cause the change in electrical configuration for all phases, the single actuator being arranged to move the or each movable body. Alternatively, multiple actuators may be used.

[0019] The movable contacts and fixed contacts may be biased together, for example by biasing the fixed contacts towards the movable contacts, and / or vice versa. This bias may be provided by one or more springs - i.e. one or more of the contacts may be spring-loaded, with the spring being arranged to push that contact towards a facing contact with which the first contact is arranged to make an electrical connection. A direction of action of the biasing may be different from the direction of movement of the actuator, for example being perpendicular thereto. The direction of action of the biasing may be different from the direction of movement of the movable body with respect to the fixed body, for example being perpendicular thereto. The biasing may be provided by spring-loading of one or more of the contacts.

[0020] The biasing force (e.g. spring force) pressing the contacts together may help to ensure good electrical contact. The spring reaction force being in a direction different from that of the movement - and preferably at least substantially perpendicular thereto - may mean that once the contacts have been moved into a selected position they stay there, without requiring any locking mechanism or actuator influence to remain in place. Good electrical contact may therefore be inherently maintained continuously, without any continued actuator force or locking mechanism. This may offer an advantage in terms of simplicity, reliability, and / or efficiency (no energy consumed to maintain contact). No separate means for ensuring continued closure of the circuit / touching of the contacts may therefore be required.

[0021] The mechanical electronic switching assembly may comprise a biasing means arranged to bias the movable contacts and fixed contacts together, wherein a direction of action of the biasing means is not parallel to a direction of movement of the actuator. The biasing means - such as one or more springs, or other elastically-compressible components - may be positioned and mounted such that a direction of action of the biasing means is not parallel to a direction of movement of the actuator, and preferably is at least substantially perpendicular thereto. The biasing means itself may provide at least one of the contacts in some embodiments.

[0022] The at least one moveable body may be arranged to move slidingly with respect to the fixed body. A surface of the movable body comprising at least one movable contact may be arranged to slide along a surface of the fixed body comprising at least two movable contacts, such that the contact pairs are sliding contacts. The movable contacts may be sliding contacts, each arranged to slidably contact at least one of the fixed contacts of the fixed body.

[0023] In implementations in which a sliding movable body is used, the movable contacts are preferably arranged to be sliding contacts - with sliding contact between the movable and fixed contacts such that the movable contacts slide across the fixed contacts, rather than a movable body sliding towards and away from the fixed contacts to make and break connections. The sliding surface may therefore be the surface including the movable contacts. The contacts may be provided with some form of spring force pressing them together to ensure good electrical contact, with the spring reaction force in a direction different from that of the sliding movement. For example, two fixed contacts may be arranged in a line (straight or curved) on a surface of the fixed body and the movable body may be slidably mounted on the fixed body, with a movable contact surface parallel and adjacent to the line on the surface of the fixed body along which the fixed contacts are located. The movable contact surface may then slide along that line, with the movable contact surface remaining in contact with the surface of the fixed body throughout its movement. The biasing force may be perpendicular to the line on the surface of the fixed body along which the fixed contacts are located, and perpendicular to the movable contact surface.

[0024] At least a region of the switching assembly which includes the fixed contacts and the movable contacts may be flooded with dielectric oil. The oil may act as both lubricant and coolant.

[0025] The movable body may comprise a contact surface, the contact surface being arranged to touch two of the fixed contacts in at least one of the first configuration and the second configuration, so forming a current path directly between the two fixed contacts. The two fixed contacts may be coplanar and in plane adjacent and parallel to a plane of the contact surface. The contact surface may therefore be described as providing two movable contacts.

[0026] At least one of the movable contacts may be arranged to touch a different fixed contact in each of the first position and the second position. Optionally the at least one movable contact may be arranged to touch two different fixed contacts in at least one of the first position and the second position. Alternatively or additionally, at least one of the fixed contacts may be arranged to touch a different movable contact in each of the first position and the second position. This re-use of contacts in different configurations (instead of requiring different contacts) may facilitate making the assembly smaller.

[0027] The movable body may comprise n pins per phase, where n is equal to the number of phase fractions of that phase, the pins providing the only movable contacts. Each pin may provide two separate conductive paths. Optionally, only a first conductive path of the pin may be used in the first configuration and only a second conductive path of the pin may be used in the second configuration. The movable contacts may be provided by a total of two electrically-separated contact faces on each pin in some embodiments. The pins may be rigidly connected together such that they move as one when the moveable body is moved between the first and second positions. The pins (or at least a pair of adjacent pins) may be rigidly connected together by a conductive link such as a busbar. The busbar may be in conductive connection with one of the two electrically-separated conductive paths provided by the pin, and may form a part of the current flow path in either the first electrical configuration or the second electrical configuration, but not both.

[0028] The mechanical electronic switching assembly may comprise, for at least one phase: two fixed contacts per phase fraction, and two conductive paths within the movable body. The movable contacts may be sliding contacts. For each phase fraction of at least this phase: in the first position, a first fixed contact may be connected to a second fixed contact by a first conductive path within the movable body, the first conductive path using at least one sliding contact (a first sliding contact), and the second conductive path within the movable body may be unused; and in the second position, the first fixed contact may be connected to a third fixed contact, instead of to the second fixed contact, by a second conductive path within the movable body, the second conductive path using at least one different sliding contact (a second sliding contact), and the first conductive path within the movable body may be unused. Optionally, the first electrical configuration is a series configuration and the second electrical configuration is a parallel configuration. In some implementations, each phase may have the same arrangement. In other implementations, and in particular for windings in a star configuration, one or more phases may have fewer contacts. For example, only one phase may have a fixed contact providing a link to the star point; the other phases may share that path and so the number of fixed contacts may be lower for the other phases. In some implementations, a sliding contact surface is provided which can touch two fixed contacts simultaneously - the corresponding current path for that position may therefore be within the fixed body except for a (generally relatively short) part provided by the sliding contact surface. There may be only a single sliding contact surface per phase fraction (e.g. for series-parallel switching), and optionally only a single sliding contact surface per phase (e.g. for delta-star switching).

[0029] The movable body may comprise a plurality of pins (one per phase fraction). For each pin, a first sliding contact may be provided by a head of the pin and a second sliding contact may be provided by a sleeve of the pin. The fixed contacts may be biased towards the pin. Optionally the current path portion from the pin’s head in the first electrical configuration may be along a core the pin, and the second sliding contact may be provided as a sleeve around the core of the pin, electrically insulated from the core. One current flow path may therefore surround the other whilst being electrically separated from it.

[0030] In alternative or additional embodiments (not purely using sliding pins) with sliding contacts, the movable body may comprise (2n-l) slidable conductive pads, for example in the form of slidable busbars, for at least one phase to provide the movable contacts, where n is equal to the number of phase fractions. In some implementations, each phase may have the same arrangement. In other implementations, and in particular for windings in a star configuration, one or more phases may have fewer contacts. For example, only one phase may have a fixed contact providing a link to the star point; the other phases may share that path and so the number of slidable conductive pads may be lower for the other phases. Each slidable busbar may provide a contact surface arranged to connect two fixed contacts in one of the first configuration and the second configuration so as to provide a current path between the two fixed contacts, and to be unused in the other of the first configuration and the second configuration. Each slidable busbar and corresponding pair of fixed contacts may be biased together. For example, each slidable busbar may be biased towards its pair of fixed contacts, the direction of the biasing optionally being perpendicular to the direction of busbar sliding. The slidable busbars may be parallel to each other, and the sliding direction may be the same for all slidable busbars. This may facilitate simple construction and actuation.

[0031] In alternative or additional embodiments (not purely using sliding contacts), the fixed body may comprise two conductors for each phase fraction, each conductor being arranged to provide at least one of the fixed contacts; and the movable body may comprise a first conductive movable part arranged to move linearly so as to make and break contact between a pair of the conductors, and a second conductive movable part arranged to move linearly so as to make and break contact between a different pair of the conductors. Either or both of the first and second movable parts many be rigid - for example being or comprising a busbar or conductive plate. The conductors may be shaped conductors (as opposed to traditional flat planar busbars, e.g. being S-shaped), the shaped conductors in particular being shaped to allow for contacts from the same conductor to be made in different places by one or more movable parts moving along at least substantially the same axis. The shaped conductors may be shaped such that the contacts they provide are spaced apart enough for one or more movable bodies, and optionally also an actuator, to be located therebetween. The shaped contacts may provide angled contact surfaces - the contact surfaces of the shaped conductor being at an angle to the direction of movement of the one or more movable bodies (an angle of between but not including 0° and 90°, e.g. between 30° and 500and optionally of around 45 °). Alternatively or additionally, the shaped conductors may be arranged and shaped to at least substantially surround the one or more movable parts. The shaped conductors may therefore both define a space for the movable bodies and provide fixed contacts for the movable bodies. The shaped conductors, optionally in combination with a base plate of the switching assembly, may therefore define a substantially enclosed space within the switching assembly.

[0032] A third movable part may be provided, arranged to move linearly so as to make and break contact between a different pair of the conductors. Alternatively or additionally, one or both of the first and second movable parts may be arranged to make and break contact between two different pairs of the conductors. In such embodiments, the actuator may comprise a rotating part - e.g. a shaft - with a cam. The rotating part and cam may lie between the first movable part and the second movable part, such that the cam pushes the first movable part in a first direction over a first angular range of rotation, and pushes the second movable part in a second direction over a second angular range of rotation. The second direction is different from the first direction, and may be opposite to the first direction. The contact surfaces of the movable parts and of the fixed conductors may be angled with respect to the first direction, optionally by around 45°, and optionally by no more than 60° - this may provide a larger contact area, and / or more reliable contact. In implementations with shaped conductors as described above, the shaped conductors may surround the shaft and cam.

[0033] According to a second aspect, there is provided a mechanical electronic switching assembly for an electric motor, said motor being a multi-phase motor comprising a winding for each phase, the windings being arranged such that each phase comprises a number of phase fractions, each phase fraction extending between a pair of terminals, the mechanical electronic switching assembly comprising: a fixed body comprising a plurality of fixed contacts each arranged to be permanently connected to a corresponding terminal of a corresponding phase fraction; at least one moveable body that can be moved slidably with respect to the fixed body between: a first position, in which the phases are arranged in a first electrical configuration; and a second position, in which the phases are arranged in a second electrical configuration, wherein the second electrical configuration is different from the first electrical configuration; and an actuator arranged to move the at least one moveable body between the first position and the second position. wherein the at least one movable body and the fixed body together are arranged to provide two different current flow paths such that the electrical configuration of phase fraction terminals can be reconfigured between the first electrical configuration and the second electrical configuration by selecting the corresponding current flow path, and wherein: the at least one movable body comprises a plurality of slidable contacts (also referred to as sliding contacts) each arranged to contact at least one of the fixed contacts of the fixed body in at least one of the first configuration and the second configuration; and at least one of the fixed contacts is arranged to be unused, in one of the first electrical configuration and the second electrical configuration. Optionally, the unused fixed contact may still touch a slidable contact in the position in which it does not form part of a current path.

[0034] The current flow path may be different within both the fixed body and the movable body between the different electrical configurations.

[0035] Any of the features describe above with respect to the first aspect may also be applied to this aspect.

[0036] According to a third aspect, there is provided a mechanical electronic switching assembly for an electric motor, said motor being a multi-phase motor comprising a winding for each phase, the windings being arranged such that each phase comprises a number of phase fractions, each phase fraction extending between a pair of terminals, the mechanical electronic switching assembly comprising: a fixed body comprising a plurality of fixed contacts each arranged to be permanently connected to a corresponding terminal of a corresponding phase fraction; at least one moveable body that can be moved with respect to the fixed body between: a first position, in which the phases are arranged in a first electrical configuration; and a second position, in which the phases are arranged in a second electrical configuration, wherein the second electrical configuration is different from the first electrical configuration, wherein the at least one movable body comprises a plurality of movable contacts each arranged to contact at least one of the fixed contacts of the fixed body in at least one of the first configuration and the second configuration, and wherein the at least one movable body and the fixed body together are arranged to provide two different current flow paths such that the electrical configuration of phase fraction terminals can be reconfigured between the first electrical configuration and the second electrical configuration by selecting the corresponding current flow path; an actuator arranged to move the at least one moveable body between the first position and the second position; and biasing means arranged to bias the movable contacts and fixed contacts together, wherein a direction of action of the biasing means is not parallel to a direction of movement of the actuator.

[0037] The direction of action of the biasing means may be perpendicular to the direction of movement of the actuator. The direction of action of the biasing means may not be parallel to a direction of movement of the movable body with respect to the fixed body, and may be perpendicular to the direction of movement of the movable body.

[0038] The current flow path may be different within both the fixed body and the movable body between the different electrical configurations.

[0039] Any of the features described above with respect to the first or second aspect may also be applied to this aspect.

[0040] According to a further aspect, there is provided a mechanical electronic switching assembly for an electric motor, said motor being a multi-phase motor comprising a winding for each phase, the windings being arranged such that each phase comprises a number of phase fractions, each phase fraction extending between a pair of terminals, the mechanical electronic switching assembly comprising: a fixed body comprising a plurality of fixed contacts each arranged to be permanently connected to a corresponding terminal of a corresponding phase fraction, wherein there are at least as many fixed contacts as there are phase fraction terminals; at least one moveable body that can be moved with respect to the fixed body between: a first position, in which the phases are arranged in a first electrical configuration; and a second position, in which the phases are arranged in a second electrical configuration, wherein the second electrical configuration is different from the first electrical configuration, wherein the at least one movable body comprises a plurality of movable contacts each arranged to contact at least one of the fixed contacts of the fixed body in at least one of the first configuration and the second configuration, and wherein the at least one movable body and the fixed body together are arranged to provide two different current flow paths such that the electrical configuration of phase fraction terminals can be reconfigured between the first electrical configuration and the second electrical configuration by selecting the corresponding current flow path, and wherein at least one movable contact of the movable body is in the form of a contact surface, the contact surface being arranged to touch two fixed contacts so as to provide a current path directly between the two fixed contacts in at least one of the first configuration and the second configuration; and an actuator arranged to move the at least one moveable body between the first position and the second position.

[0041] According to a fourth aspect, there is provided an electric motor comprising a rotor, a stator, and the mechanical electronic switching assembly of any preceding aspect, optionally mounted on the stator of the electric motor.

[0042] According to a fifth aspect, there is provided a wheel assembly for an electric vehicle, the wheel assembly comprising a wheel and the electric motor of the fourth aspect, and wherein the rotor or stator of the motor is mounted to the wheel, optionally rigidly. An electric vehicle comprising one or more such wheel assemblies may also be provided.

[0043] According to a sixth aspect, there is provided an electric vehicle comprising a chassis, a wheel, and a motor as claimed in the fourth aspect. The motor may be (i) mounted to the chassis; or (ii) mounted to the wheel.

[0044] Features described with respect to one aspect of the invention may be applied to any other aspect of the invention, mutatis mutandis. There now follows by way of example only a detailed description of embodiments of the present invention with reference to the accompanying drawings in which:

[0045] Figure 1 (illustration of PRIOR ART) shows an electrical schematic for switchable motor windings, switchable between series and parallel star configurations, and a simplified view of the coil interconnections provided in each of the two configurations;

[0046] Figure 2 shows an electro-mechanical switching assembly of an embodiment;

[0047] Figure 3 shows a sectional perspective view of an electro-mechanical switching assembly in which the movable contacts are provided by sliding pins; Figure 4A shows a close-up of a portion of the electro-mechanical switching assembly of Figure 3 with the pins in a first position, so as to provide a series electrical configuration of phase fractions;

[0048] Figure 4B shows a close-up of a portion of the electro-mechanical switching assembly of Figure 3 with the pins in a second position, so as to provide a parallel electrical configuration of phase fractions;

[0049] Figure 5 shows the sectional perspective view of Figure 3 with the current path for the series configuration marked with arrows;

[0050] Figure 6 shows a close-up sectional view of a pair of adjacent pins in the electro-mechanical switching assembly of Figure 3, with the series current flow path marked;

[0051] Figure 7 shows a sectional perspective view corresponding to Figure 3, but in the parallel configuration, with the current path for the parallel configuration marked with arrows;

[0052] Figure 8 shows a sectional perspective view corresponding to Figure 4A, with labelled contacts;

[0053] Figure 9A shows the electrical schematic for the electro-mechanical switching assembly of Figures 3 to 8 in the series configuration, with current flow marked for the first phase only;

[0054] Figure 9B shows the electrical schematic for the electro-mechanical switching assembly of Figures 3 to 8 in the parallel configuration, with current flow marked for the first phase only;

[0055] Figure 10 shows a perspective view of an electro-mechanical switching assembly in which the movable contacts are provided by sliding pads / planar contacts;

[0056] Figure 11A shows a close-up of a portion of the electro-mechanical switching assembly of Figure 10 with the pads in a first position, so as to provide a series electrical configuration of phase fractions;

[0057] Figure 11B shows a close-up of a portion of the electro-mechanical switching assembly of Figure 10 with the pads in a second position, so as to provide a parallel electrical configuration of phase fractions;

[0058] Figure 12 shows a close-up view of the electro-mechanical switching assembly of Figure 10 in the first position, with the series current flow path marked;

[0059] Figure 13 shows a close-up view of the electro-mechanical switching assembly of Figure 10 in the second position, with the parallel current flow path marked;

[0060] Figure 14 shows a portion of the electro-mechanical switching assembly of Figure 10 with the pad used in the series configuration for the first phase circled in dark grey, and the pads which are used in the parallel configuration for the first phase circled in a lighter grey;

[0061] Figure 15 shows a close-up sectional view of one of the pads of Figure 10, showing the biasing of the movable pad towards the fixed contacts;

[0062] Figure 16A shows the electrical schematic for the electro-mechanical switching assembly of Figures 10 to 15 in the series configuration, with current flow marked for the first phase only;

[0063] Figure 16B shows the electrical schematic for the electro-mechanical switching assembly of Figures 10 to 15 in the parallel configuration, with current flow marked for the first phase only;

[0064] Figure 17 shows a perspective view of an electro-mechanical switching assembly in which the movable contacts are provided by two separate moving parts located to either side of a rotary actuator;

[0065] Figure 18A shows a sectional view of the electro-mechanical switching assembly of Figure 17 with the rotary actuator in a first position, so as to provide a series electrical configuration of phase fractions;

[0066] Figure 18B shows a sectional view of the electro-mechanical switching assembly of Figure 17 with the rotary actuator in a second position, so as to provide a parallel electrical configuration of phase fractions;

[0067] Figure 19 shows a close-up view of the electro-mechanical switching assembly of Figure 17 in the first position, with the series current flow path marked; Figure 20 shows a close-up view of the electro-mechanical switching assembly of Figure 17 in the second position, with the parallel current flow path marked;

[0068] Figure 21 shows a sectional view of the electro-mechanical switching assembly of Figure 17 with pairs of contacts above and below the rotary actuator marked;

[0069] Figure 22A shows the electrical schematic for the electro-mechanical switching assembly of Figures 17 to 21 in the series configuration, with current flow marked for the first phase only;

[0070] Figure 22B shows the electrical schematic for the electro-mechanical switching assembly of Figures 17 to 21 in the parallel configuration, with current flow marked for the first phase only;

[0071] Figure 23A shows an electrical schematic for an embodiment using a switching assembly as for Figures 3 to 8, but with the circuitry configured to provide delta-star switching instead of series-parallel switching, in a first position corresponding to a star configuration, alongside a simplified diagram of a star configuration;

[0072] Figure 23B shows an electrical schematic for the embodiment of Figure 23A, in a second position corresponding to a delta configuration, alongside a simplified diagram of a delta configuration;

[0073] Figure 24A shows an electrical schematic for an embodiment using a switching assembly as for Figures 3 to 8, but with an additional movable body; the circuitry being configured to provide delta-star switching as well as series-parallel switching, in a first position corresponding to a series-star configuration;

[0074] Figure 24B shows an electrical schematic for the embodiment of Figure 24A, in a second position corresponding to a parallel-star configuration;

[0075] Figure 24C shows an electrical schematic for the embodiment of Figure 24A, in a third position corresponding to a series-delta configuration;

[0076] Figure 24D shows an electrical schematic for the embodiment of Figure 24A, in a fourth position corresponding to a parallel-delta configuration;

[0077] Figure 25 shows a cross-sectional view of an electro-mechanical switching assembly similar to that shown in Figure 3, but with a different position of the busbars between pins;

[0078] Figure 26 shows a different cross-sectional view of the electro-mechanical switching assembly of Figure 25, in the series configuration;

[0079] Figure 27 shows a different cross-sectional view of the electro-mechanical switching assembly of Figure 25, in the parallel configuration;

[0080] Figure 28 shows a perspective view of the electro-mechanical switching assembly of Figure 25, from behind;

[0081] Figure 29 shows a perspective view of the electro-mechanical switching assembly of Figure 25, from behind, with a cover plate removed;

[0082] Figure 30 shows a perspective view of the electro-mechanical switching assembly of Figure 25, from the front;

[0083] Figure 31 shows a perspective view of the electro-mechanical switching assembly of Figure 25, from the front, with inverter connectors in place;

[0084] Figure 32 shows a cross-sectional view of a part of a wheel assembly for a vehicle, showing the electromechanical switching assembly of Figure 25, mounted on the stator of a motor;

[0085] Figure 33A shows an alternative electrical schematic for an embodiment similar to that of Figure 23 but with a different electrical configuration in the fixed body, in a first position corresponding to a star configuration; and Figure 33B shows an alternative electrical schematic for the embodiment of Figure 33A, in a second position corresponding to a delta configuration.

[0086] Figure 1 is a diagram provided to show prior art approaches to switching of windings by way of example to facilitate later explanation of embodiments of the invention. Figure 1 shows a known electrical schematic for a motor 1 with three-phase switchable windings, with phases labelled Phase A, Phase B, and Phase C. Each phase has two coils, labelled Al and A2 for Phase A, B l and B2 for Phase B, and Cl and C2 for Phase C. Each coil may be referred to as a phase fraction - each phase has two phase fractions in this example. An inverter 10 provides power to the motor windings 1.

[0087] Each coil Al, A2, ... has a terminal, T, at each end thereof. The terminal, T, is used to connect the respective end of that coil to associated circuitry (e.g. one or more wires, busbars, switches, and / or other circuit components) as shown in the electrical schematic.

[0088] The motor windings 1 shown in the schematic 1 of Figure 1 are arranged in a star configuration, and are switchable between a series configuration, S, and a parallel configuration, P. These configurations may be referred to as a series-star configuration and a parallel-star configuration, respectively. In the series configuration, S, coil Al is in series with coil A2, coil B l is in series with coil B2, and coil Cl is in series with coil C2. In the parallel configuration, P, coil Al is in parallel with coil A2, coil B l is in parallel with coil B2, and coil Cl is in parallel with coil C2.

[0089] A plurality of switches S, P, are provided to enable the configuration switching. When all of the switches marked S are closed and all of the switches marked P are open, the windings in each phase are connected in series. When all of the switches marked P are closed and all of the switches marked S are open, the windings in each phase are connected in parallel. A mechanism is used to open or close the switches S, P. In general, the mechanism may be arranged to ensure that the switches cannot all be closed simultaneously, as this could short the windings. The mechanism may be arranged to allow all of the switches to be opened simultaneously, however - breaking the circuit. This may be particularly useful as a safety feature should a fault develop. Any suitable actuation mechanism may be used.

[0090] Three switches per phase are used in this prior art example - more switches would be needed for windings with more than two coils per phase.

[0091] Figure 2 shows a perspective view of a switching assembly 100 for a motor. The switching assembly 100 shown comprises a terminal block 101 with twelve connectors 102 to which phase fraction terminals, inverter input, and junction points between phases (e.g. in the case of star configurations of phases, the star point) can be connected. The twelve connections 102 are arranged in a grid with two rows of six in this example, the connectors being aligned horizontally and vertically.

[0092] Here, we note that the number of connectors 102 wanted will generally depend on the number of electrically-separable coils, also referred to phase fractions, of each phase, with each phase fraction having two ends (one at / before the start of the coil, in the direction of current flow, and the other at / after the end of the coil, in the direction of current flow). Generally each coil may be provided with a terminal, T, at its start and its end so as to allow the configuration of that coil to be adjusted with respect to all other coils. (In some implementations, two or more physically-distinct coils may be contained within a single phase fraction, with terminals only before the first coil and after the last coil, but no terminals between the first and second coils. This pair of physical coils is therefore not electrically-separable and is classed as a single coil from an electrical perspective.) The total number of connectors 102 provided in implementations in which configurations of phase fractions are to be changed may therefore be at least N(2n), where n is the number of phase fractions and N is the number of phases (n may vary between phases in some embodiments, and a sum over the phases may then be performed). For example, for a standard three-phase arrangement with two coils per phase, a total of four connections per phase may be provided, for a total of twelve connections. In implementations where the phases remain in a star configuration (e.g. with switching from series-star to parallel-star), the number of connectors 102 can be reduced so as to have only one connection to the star point, shared by all of the phases. In this case, there may be a total of N(2n-1)+1 connectors. For the 3-phase, two phase fraction, example (N=3, n=2) this would mean using ten connectors 102 rather than twelve, even though there are still twelve phase fraction terminals, T. The number of connectors may be reduced significantly further in arrangements in which phase fractions are left in series or parallel - e.g. for star-delta switching.

[0093] In the example being described, the phases are arranged in a star configuration, and each phase has four connectors 102a, 102b, 102c, 102d. These four connectors 102a-d (labelled only for one phase for clarity; each set of four corresponds to the same arrangement of a different phase) are arranged as a square of adjacent connectors in the assembly as shown in Figure 2. The first connector 102a is connected to a terminal of a first phase fraction N1 of the respective phase N, the second connector 102b is connected to a junction point between phases, which in this case is the star point, the third connector 102c is connected to a terminal of the coil for the second phase fraction N2 of the respective phase N, and the fourth connector 102d is connected to an inverter input (in this implementation, via a pin inserted from behind the switching assembly 100, if the face shown in Figure 2 is taken to be the front), and also to the terminal of the first phase fraction N1 of the respective phase N which is not connected to the first connector 102a. The terminal of the second phase fraction N2 of the respective phase N which is not connected to the third connector 102c is connected to the star point, and thereby also to the second connector 102b. The second connector 102b is therefore connected to both a terminal of the second phase fraction N2 and the star point. In this example, the phases are arranged in a star configuration, so the current path for each phase terminates at the star point inside the associated motor. Starting from the inverter input, the fourth connector 102d is where the inverter is connected to the switching assembly 100, and is also connected to the start of the N1 coil, the first connector 102a is connected to the end of the N1 coil, the third connector 102c is connected to the start of the N2 coil, and the second connector 102b is connected to the end of the N2 coil, and to the star point. In the square arrangement of connectors 102a-d as shown in Figure 2, the coils are therefore effectively located across diagonals of the square (102d to 102a, and 102c to 102b) rather than along the sides. It will be appreciated that the physical arrangement of the connectors 102 may vary between implementations.

[0094] The connectors 102a, 102b, 102c, 102d serve to connect the internal circuitry of the switching assembly 100 to external current flows (e.g. input from an inverter, and output to coils of a motor). The connectors 102a, 102b, 102c, 102d may be referred to as terminal points or terminal connectors, as they are intended to be connected to the terminals of phase fractions. A cover 103 for an actuator 152 (described later) mounted on the terminal block 101 is also shown. The actuator 152 of various implementations may be, for example, a solenoid actuator, or a Voice Coil. Any suitable actuation design known in the art may be used - a solenoid actuator was selected for the example pictured in Figure 2. The cover 103 of this implementation protrudes from the terminal block 101 and provides a widest part of the assembly 100. The actuator 152 is located centrally with respect to the connectors 102 in this example, but may be positioned differently, e.g. at one end of the terminal block 101, in other implementations. In this example, the terminal block 101 has a length, L, in the range from 10 to 25 cm, and more specifically of 17 cm, a width, W, in the range from 2 to 12 cm, and more specifically of 5 cm and a height, H, in the range from 3 to 12 cm, and more specifically of 7.6 cm. The actuator 152, 103 extends from one side of the terminal block 101 by around 3.5 cm, so extending a maximum width of the assembly 100 to around 8.5 cm, including the actuator. The actuator 152, 103 shown has a diameter in the range from 2 to 8 cm, and more specifically of around 2.6 cm. In implementations using a Voice Coil motor actuator, the extra region 103 for the actuator 152 may be larger - for example with a width of around 3 cm and a diameter of around 5 cm. Actuator shapes may also vary in other implementations; for example not being cylindrical. In various implementations, the terminal block 101 may have a length (longest dimension) no greater than 20 cm, and optionally below 18 cm, a width no greater than 10 cm, and optionally below 8 cm, and a height no greater than 15 cm, and optionally below 12 cm.

[0095] Figure 3 shows a sectional perspective view of the electro-mechanical switching assembly 100, showing two of the connections 102a, 102b within the terminal block 101. The electro-mechanical switching assembly 100 is for a 3 -phase motor, and the three phases are referred to herein as A, B and C. It will be appreciated that the same principles can be applied with different numbers of phases. In the embodiment shown in Figure 3, each connector 102a-d is in the form of a conductive socket passing through the switching assembly, arranged to receive one or more pins or other “plugs” compatible with the socket. In other implementations, such as that shown in Figures 25 to 32, each connector 102a-d may instead be in the form of a pin extending through the switching assembly.

[0096] In the embodiment shown in Figure 3, the first connector 102a of the set of four connectors 102 for phase B is connected to a second terminal of a first phase fraction (B l) of the second phase, B (the first terminal of that phase fraction B 1 being connected to an inverter input, in this implementation via the fourth connector 102d to avoid a separate connection to the inverter input being needed). In the embodiment shown, the second connector 102b is connected to the star point between phases, to which a second terminal of a second phase fraction (B2) of the second phase, B, is also connected. The third connector 102c is connected to the first terminal of the second phase fraction (B2). In this example, each phase A, B, C has two phase fractions; it will be appreciated that the same principles can be scaled for different numbers of phase fractions.

[0097] Within the terminal block 101, electrical connections are made - some of these connections are permanent, whereas others are movable / switchable, so allowing the electro-mechanical switching assembly 100 to function. Switchable connections are provided between pairs of contacts - one movable contact and one fixed contact. As used herein, “contacts” refers to the conductive regions providing these switchable connections, and not to meetings of conductors at permanent connections (e.g. where secured together e.g. by welding, or otherwise permanently touching). In the embodiment shown in Figure 3, each connector 102a, 102b is permanently connected to a respective conductor 122a, 122b within the terminal block (the same applies for connectors 102c and 102d, with conductors 122c and 122d respectively, which can be seen in Figure 6). The conductors 122a, 122b comprise metal bars (e.g. busbars) or prongs in the example pictured (although wires and / or different forms or materials of conductors may be used in other examples), and extend downwardly (in the orientation shown) from their respective connector 102a, 102b to the same level, so allowing fixed contacts (one for each connector 102a, 102b) to be provided at the same vertical position (in the orientation shown) within the terminal block 101. These conductors 122a, 122b each effectively provide an extension to the connector 102a, 102b to which that conductor 122a, 122b is permanently attached, so as to provide a fixed contact in a more convenient location for the switching assembly 100. It will be appreciated that a differently-shaped connector 102a, 102b, and / or different pin position, could lead to either or both of these conductors 122a, 122b being redundant.

[0098] In the example pictured, each conductor 122a, 122b comprises a contact 124a, 124b biased downwardly - in this example by a coil spring, although it will be appreciated that any suitable biasing means may be used, such as a leaf spring, a compressed elastic material, or similar - so as to press against a movable contact therebeneath, improving the electrical connection. This contact 124a, 124b is described as a fixed contact because its location within the terminal block 101 is substantially fixed - the small amount of movement allowed by the biasing means does not significantly change its location, but rather ensures that it is firmly held in place.

[0099] The electro-mechanical switching assembly 100 also comprises a plurality of movable pins 130. The pins 130 may be described as selector pins 130, as they allow a desired current path within the terminal block 101 to be selected between. The pins 130 provide movable contacts, which can selectively make contact with the fixed contacts 124. The pins 130 may be individually movable in some implementations, but are rigidly connected together to form a single movable body in the implementation pictured. In the present example, the pins 130 are each oriented across the width of the terminal block 101, parallel to each other and spaced along the length of the terminal block 101. The pins 130 are connected together tip-to-tip, by a bar extending along the length of the terminal block 101, perpendicular to the length of each pin 130. The pins 130 may be differently-aligned in other implementations; for example the pins 130 may be aligned coaxially in a single row, effectively forming a single prong, or long pin, which patches the relevant pairs of contacts to each other.

[0100] In the embodiment being described, one pin 130 is provided for each pair 102a, 102b of connectors, and the pin 130 passes through an opening in each conductor 122a, 122b (the second pair 102c, 102d of the group of four connectors 102 similarly has its own pin between conductors 122c, d as can be seen most clearly in Figure 6). Each fixed contact 124a, 124b may therefore be arranged to touch the pin 130 in more than one place - e.g. from above and from below in the orientation shown - to further improve contact. Multiple biasing means may be provided as appropriate. The number of pins 130 provided is equal to the number of phase fractions in this implementation - if a phase were divided into three fractions rather than two, an additional pin would be provided.

[0101] Each selector pin 130 comprises a conductive head 131 and shaft 134 (which together may be referred to as the pin’s core), an insulating layer 132 surrounding the conductive shaft, and a conductive sleeve 133 mounted on the insulating layer 132, and insulated from the pin’s core by the insulating layer 132. The head 131 provides a first movable contact 131 and the sleeve 133 provides a second movable contact 133.

[0102] In the implementation pictured, the insulating layer 132 and sleeve are sized and arranged such that a diameter of the pin 130 is constant along a first portion of the pin’s length, including the head - the insulating layer 132 matches the diameter of the head in a region adjacent to the pin’s head, and then reduces in diameter to allow space for the sleeve 133 further along the shaft. The sleeve 133 is sized to keep the pin’s diameter constant along the length of the sleeve 133. Near the pin’s tip, the pin’s diameter reduces. In the example pictured, at the far end of the sleeve 133 from the head 131, the insulating layer 132 does not increase in diameter again to make up for the sleeve ending, so providing a reduced diameter (in other implementations, the insulating layer 132 may briefly increase in diameter to provide an end-stop for the sleeve, before then reducing again), and the insulating layer 132 ends before the pin’s tip, so providing a further reduced diameter. The first reduction in diameter provides a step which may be used to limit lateral movement of the pin 130. The second reduction in diameter (exposing the conductive shaft 134) may be beneficial in making an electrical connection at or near the pin’s tip.

[0103] In the implementation pictured, at the end of the conductive sleeve 132 the remaining portion of the pin 130 is embedded in a bar 140, the bar 140 being arranged to move with respect to the terminal block 101. Each pin 130 is rigidly connected to the bar 140, the pins 130 and bar 140 together forming a movable body 150. The bar 140 comprises a body made of an insulating material, with a plurality of busbars 145 embedded therein or mounted thereon. Each busbar 145 contacts the conductive shafts 134 of a pair of adjacent pins 130, so providing a permanent connection between pin cores. The tip of each pin 130 is received in a corresponding aperture in the busbar 145 in the implementation pictured. A current path is therefore available from one pin 130 to the next, within the movable body 150.

[0104] The movable body 150 is arranged to move horizontally between a first position as shown in Figure 4A, and a second position as shown in Figure 4B (herein, all mentions of horizontal, vertical, upper, lower, left, right, etc. refer to the orientation shown in the figures for ease of discussion and are not limiting).

[0105] In the first position, the bar 140 rests against stops 101a provided by the terminal block 101. In the first position, the head 131 of the pin 130 is in electrical contact with the first conductor 122a - the movable contact 131 touches the fixed contact 124a to provide a current flow path from the connector 102a to the pin’s core, and onward through the movable body 150. Herein, the term “current flow path” indicates a physical path along which current can flow, irrespective of current flow direction (especially given that current flow is often alternating - AC power - the skilled person would appreciate that it is the physical arrangement of conductive elements that forms the path, with the flow direction being irrelevant). When paths are said to be different, what is relevant is therefore the path having a different physical route, at least one difference in components making up the path, one or more different interconnections with the same parts, and the use of one or more different contacts on one body with a given current path in a relatively movable body - i.e. physical differences in the conductors, or portions of conductors, used to form the path rather than differences in the current flow itself - the current flow path may therefore equivalently be referred to as a conductive pathway. The sleeve 133 of the pin 130 touches the fixed contact 124b of the second conductor 122b, but the sleeve 133 is otherwise surrounded by insulating material and so this is a “dead end” and no current flows - the connector 102b is therefore unused in this position. In some embodiments, the sleeve 133 of the pin 130 may not touch the fixed contact 124b of the second conductor 122b in the first position, although it will be appreciated that allowing contact to be maintained (although unused) may help to reduce system size.

[0106] In the second position, the bar 140 is closer to the connectors 102a, 102b, and rests against the closest conductor 122b (in the bar’s upper region) and against a stop 101b provided by the terminal block 101 (the terminal block 101 may be shaped to avoid contact between the bar 140 and the closest conductor 122b in other embodiments). In the second position, the head 131 of the pin 130 does not touch any fixed contacts, and the path of electrical continuity along the pin’s core and through the busbar 145 to an adjacent pin is unused / no current flows through the pin’s core or along the bar 140. By contrast, the pin’s sleeve 133 touches both the first fixed contact 124a and the second fixed contact 124b, so providing a direct connection between the first and second conductors 122a, 122b, and thereby between the first and second connectors 102a, 102b. The current flow path within the movable body 150 in this position is therefore purely within the sleeve 133. The arrows in Figures 4A and 4B indicate the direction of movement of the movable body 150 with respect to the fixed body 101 provided by the terminal block 101. The diameter of the pin 130 is constant along a first portion of the pin’s length, and the length of that first portion is set to be at least equal to the maximum displacement of the pin as the movable body 150 moves with respect to the fixed body 101, so providing smooth, sliding, contact with the fixed contacts 124. As the pin 130 is moved from the first portion to the second position, the first fixed contact 124a initially touches the head 131, and then the insulating layer 132, and then the conductive sleeve 133, without changing position. Any minor surface roughness of the pin 130, or other minor variation in diameter, can be accommodated by the biasing means, so maintaining smooth, sliding contact throughout the movement.

[0107] The movable body 150 may be slidably mounted on the fixed body 101.

[0108] Figure 5 illustrates the current flow path in the first position of the movable body 150. Input from an inverter for the second phase (B) is marked by the letter B within an arrow. This current flows through the coil for the first phase fraction B l of phase B, and then to the first connector 102a, to which the phase fraction terminal of the coil for the first phase fraction B l of phase B is connected. From the first connector 102a, current flows down the conductor 122a and to the first fixed contact 132a. The first fixed contact 132a is touching the head 131a of the pin 130a, so current flows into the pin’s core, along the shaft 134, and into the busbar 145 which connects the core of that pin 130a to the core of an adjacent pin 130c (of which only the tip can be seen in Figure 5, although both pins are shown in Figure 6, which shows more clearly how the current passes from one pin 130a to the adjacent pin 130c, through the connecting busbar 145). Current then flows along the core of the adjacent pin 130c, to a fixed contact 124c in contact with the head 131c of that pin 130c. The fixed contact 124c is part of a conductor 122c arranged to provide a permanent connection to the connector 102c, and thereby to a terminal of the second phase fraction B2 of phase B. Current therefore flows from the first coil B l, though the terminal block 101 following the selected current path, and to the second coil B2, before reaching the star point between phases. Current leaving the second coil B2 flows to the star point at which the phases are connected. Coils B l and B2 are therefore arranged in series. Connector 102b and its corresponding conductor 122b and fixed contact 124b are unused in this configuration.

[0109] In this first position, the phases are therefore arranged in a configuration in which their phase fractions are connected in series. The current from the inverter for each of the phases arrives near the top of the switching assembly 100 and passes straight through the switching assembly 100 (by means of a pin inserted into the socket connector 102d in the implementation being described) into the first phase fraction (e.g. B l), returning at the bottom contact 102a. From there, it passes through the head 131a of the sliding pin 130a, through the pin’s central shaft 134 to the busbar 145. It passes along the busbar 145 and through the second pin 130c in the opposite direction to current flow direction through the first pin 130a, through the second bottom contact 102c, and into the second phase fraction (B2). The current flow path for this phase, B, terminates at the star point inside the motor after leaving the second phase fraction, B2. This first electrical configuration may therefore be referred to as a series configuration. The electrical schematic for this is shown in Figure 9A, which is discussed in more detail below.

[0110] Figure 7 illustrates the current flow path in the second position of the movable body 150. Input from the inverter for the second phase (B) is again marked by the letter B within an arrow. This current flow is split in two directions - (i) through the coil for the first phase fraction B l of phase B, and then to the first connector 102a, to which the terminal of the coil for the first phase fraction B l of phase B is connected (as in the first position) but also (ii) to the coil for the second phase fraction B2 of phase B. From the first connector 102a, current flows down the conductor 122a and to the first fixed contact 132a. Unlike in the series configuration, the first fixed contact 124a is not touching the head 131a of the pin 130a, but instead is touching the sleeve 133a of the pin 130a. Current flows along the sleeve 133a of the pin 130a, to the fixed contact 124b in contact with the second conductor 122b, and thereby to the second connector 102b which is connected to the star point.

[0111] Simultaneously, current from the inverter input flows from connector 102d down the permanently- joined conductor 122d for that connector, and to the fourth fixed contact 124d which is in contact with the sleeve 133c of the adjacent pin 130c. Current flows along the sleeve 133c of the pin 130c, to the fixed contact 124c in contact with the third conductor 122c, and thereby to the third connector 102c which is connected to the coil for the second phase fraction B2 of phase B. Current leaving the second coil B2 then reaches the star point between phases. Current therefore flows through two separate loops extending between the inverter input and the star point - the first loop including the first coil B l and the first pin 130a (more specifically, the sleeve 133a of the first pin), and the second loop including the second coil B2 and the second pin 130c (more specifically, the sleeve 133c of the second pin). Coils B l and B2 are therefore arranged in parallel.

[0112] In this second position, as in the first position, current from the inverter for each of the phases arrives near the top of the switching assembly 100, and is immediately split, with half flowing straight through the switching assembly 100 and into the coil for the first phase fraction B l, and the other half flowing downwards along one conductor 122d, then through the outer sleeve 133c of the corresponding pin 130c, which bridges into the start of phase fraction B2 via the connector 102c. This second position uses the pins’ outer sleeves 133, and not the head 131 and shaft 134 or the busbar 145 which links adjacent pins

[0113] 130. In this second position, the phases are therefore arranged in a configuration in which their phase fractions are connected in parallel. This second electrical configuration may therefore be referred to as a parallel configuration. The electrical schematic for this is shown in Figure 9B, which is discussed in more detail below.

[0114] The switching assembly 100 of this implementation is therefore arranged to switch the phases between a series configuration of their phase fractions and a parallel configuration of their phase fractions.

[0115] Two fixed contacts 124a and 124c of the four fixed contacts 124 per phase are used in both the series configuration and the parallel configuration, albeit in connection with different movable contacts

[0116] 131, 133. This re-use of the same fixed contacts 124a, c in two configurations may help to reduce system size and / or cost. In this example, two of the movable contacts - the heads 131 of an adjacent pair of pins 130 - are linked via a path entirely within the movable body 150. For each phase, a total of three conductive paths within the movable body 150 is therefore provided - one pin head to pin head, and one each along the sleeve 133 of each pin. This can be thought of as each phase fraction having two associated conductive pathways, but one of the pathways (pin head to pin head) is used to join phase fractions, and so is associated with two phase fractions - the number of different conductive pathways is therefore less than twice the number of phase fractions, and may be 2n-l, where n is the number of phase fractions.

[0117] In the electrical schematics (Figures 9A and 9B) input from an inverter for each phase (A, B, C) marked by the corresponding letter within an arrow. For the first phase (A) only, arrows are used to indicate the direction of current flow, and unused conductive paths are shown in grey whereas conductive paths along which current is flowing are shown in black. The same applies to the later phases but the current flow and path usage is not marked, for clarity. For the second phase only (B) reference numbers are marked for the fixed 124a-d and movable 131a,c, 133a, c contacts. A dashed line is used to indicate the rigid coupling of the movable components 130a, b, 140, 145 which together form the movable body 150, with a double-headed arrow indicating the movement of the movable body 150 between the first and second positions. In these schematics, the bottom rail is effectively the “Star Point”. In physical implementations, it is unlikely that there would be elongate sections of conductor in between the bottom of each phase (the black dots along this rail); the terminals of the three phases and the cable(s) to link from there to the switching assembly might instead be crimped together, for example. The star point is simply shown extended to this rail for ease of representation. However, it will be appreciated that intermediate joining conductors could be used in some physical implementations (so more closely matching the schematic) without changing the functioning of the apparatus. The second connector 102b may therefore connect to the terminal of the second phase fraction N2 at or via the star point, or along a conductor leading to the star point, for example - the precise location of wire splices or other inter-phase links may therefore vary without affecting performance.

[0118] As can be seen from comparing Figures 9A and 9B, two fixed contacts 124b, 124d are unused in the series configuration, such that two of the connectors 102b, 102d are also unused (at least insofar as they connect to the internal circuitry of the switching assembly - see following paragraph). By contrast, in the parallel configuration all fixed contacts 124a-d are used. The current path within the fixed body 101 is therefore different between the two configurations. Similarly, the current path within the movable body 150 is different between the two configurations as the sleeve 133 of each pin 130 is used only in the parallel configuration, and the core 131, 134 of each pin 130 is used only in the series configuration.

[0119] Connector 102d is connected to both an inverter input and a terminal of the first phase fraction B l of the respective phase B. This connector 102d still provides a current flow path from the inverter to the phase fraction B l even when it is unused in the context of the switching assembly 100 - it will be appreciated that this current flow path (inverter to B l) simply passes straight through the terminal block 101 from front to back.

[0120] Embodiments like that shown in Figure 3 therefore use sliding pins 130 which move between two positions. The pins 130 are in pairs (e.g. 130a, 130c) which are connected by conductive busbars 145. Each pin 130 has two separate conductive paths - a first path from the pin’s head 131, along a shaft of the pin 134, and to the busbar 145, and a second path along the pin’s sleeve 133 which is electrically separated from the pin’s shaft 134. In the first, series, position, the first path 131, 134, 145 is used, and the second path (along the sleeve 133) is not used. In the second, parallel, position, the first path 131, 134, 145 is not used - instead, the sleeve 133 provides the short, conductive, second path bridging between two fixed contacts 124a, 124b, which are each provided as canted coil spring contacts in the embodiment pictured. In the embodiment pictured, the canted coils springs provide the only physical contact between the fixed contacts 124a, 124b and the conductive pathways of the pins 130, so all current flows through the coil springs. Especially in the series position, the current may be relatively high and the relatively small cross-sectional area of the coil spring may result in unwanted Joule heating (resistive heating) of the contact. A shaped portion of the pin 130, for example a “lip” or ridge on the pin 130 may therefore be provided to make contact with the conductor 122a on which the coil spring is mounted, so increasing the overall cross-sectional area of the electrical contact and so reducing Joule heating. A corner of the conductor 122a nearest the lip on the pin may be slanted / angled, or otherwise shaped, so as to provide a larger contact surface for the lip on the pin. The lip may increase the pin’s circumference sufficiently that the pin cannot move further to the right than the position in which the lip on the pin touches the conductor 122a, and may therefore define a limiting position for the pin 130 in the first position. In some implementations with such a lip, the pin 130 may be biased towards the conductor 122a (actively or passively) so as to improve contact. In some implementations, a similar lip may be provided for the second (parallel) position, to increase the contact area between the parallel current pathway 133 of the pin 130 and the respective conductor 122b. The lip or ridge may be on the pin 130 itself - optionally on the shaft of the pin, and may be provided as a continuous circumferential ridge, or may be provided as a series of discrete protrusions around the circumference of the pin. Alternatively (or additionally) a shaped portion of the conductive busbar 145 which connects an adjacent pair of pins 130 may provide the additional contact area. One such example is described in more detail below with respect to Figures 25 to 27, for a slightly different pin design - it will be appreciated that the same principle could be implemented for the implementation of Figure 3.

[0121] As shown in Figure 9, for three phases with two phase fractions apiece, a total of six movable pins 130, each providing two movable contacts (head 131 and sleeve 133) are used, therefore making 12 “switches”. Whilst this is more than the standard nine switches shown in the electrical schematic of Figure 1, the reconfigured electrical connections allow the switching assembly 100 to be more compact. The use of sliding contacts, and of fixed contact surfaces which are used in both configurations, means that there are only twenty-four contact surfaces in total (six movable pins each with two contacts gives twelve movable contacts, plus twelve fixed contacts). If the sleeve 133 of each pin 130 is counted as two contacts, the total is thirty contacts (six movable pins each with two contacts gives eighteen movable contacts).

[0122] As the sleeve 133 of each pin 130 is able to provide a bridge between two fixed contacts 124a, 124b - with the same conductive contact surface 133 touching both fixed contacts 124a, 124b - a total number of contact surfaces required may therefore be reduced, so allowing the switching mechanism 100 to be made simpler, cheaper, and / or smaller. In addition, as the contact is sliding contact with a direction of movement of the sliding being parallel to the pin’s length 130 / along the contact surface 133 and a direction of the electrical flow from the fixed contact to the movable contact being at least substantially perpendicular to the pin’s length 130 and to the contact surface, biasing the fixed and movable contacts together does not risk moving the pin 130, as the direction of the biasing force is at least substantially perpendicular to the direction of pin movement. No lock may therefore be needed to hold the pin 130 in each of the first and second positions, and an actuator 152 controlling the movement may be deactivated between movements / only powered during the act of switching positions. Indeed, the biasing means (where present) may assist in holding the pin 130 in each position by increasing friction and so reducing the chance of the pin 130 slipping when not being deliberately moved.

[0123] In the embodiment being described, an actuator 152 (indicated in Figures 9 A and 9B) is used to move the movable body 150 (and therefore the pins 130) backwards and forwards between the first and second positions as desired. A linear actuator 152 is used in this example. A solenoid actuator 152 built into the terminal block 101 is used in this embodiment; it will be appreciated that any suitable actuator type and location may be used in other embodiments.

[0124] In this implementation 100, the pin head 131 forms a part of the current flow path in the first, series, configuration, but not in the second configuration. In the series configuration, the pin head 131 carries current from a fixed contact 124a it touches to the joining busbar 333, and then to an adjacent pin 130. In the parallel configuration, the pin head 131 is no longer touching a fixed contact. The slidable contact 131 provided by the pin’s head 131 therefore touches one fixed contact in the first position but no fixed contacts in the second position.

[0125] In this implementation 100, the sleeve 133 forms a bridge between two fixed contacts 124 in one position (the parallel configuration) - two fixed contacts 124a-b touch the movable contact 133 in the second position. In the series configuration, the sleeve 133 is unused as a current path and no current flows through the second fixed contact 124b. In the example shown, the slidable contact 133 nonetheless remains touching the second fixed contact 124b (albeit with a different part of the sleeve 133). The slidable contact 133 therefore touches one fixed contact in the first position and two fixed contacts in the second position. This may help to allow the apparatus 100 to remain compact, but in other implementations the pin 130 may move further, and / or the sleeve 133 may be shorter, and the sleeve 133 may not touch any fixed contacts 124 in the position in which it is unused.

[0126] In this implementation 100, the first fixed contact 124a therefore is used / forms part of the current path within the switching assembly 100 in both the first position and the second position - it is always connected, but is connected by a different movable contact 131, 133 such that its connectivity is re-routed. This may again be beneficial in reducing the size of the switching assembly 100.

[0127] Due to each pin 130 providing two different current flow paths, a total of two movable pins can be used to replace the three switches per phase generally used when there are two phase fractions per phase (as shown in Figure 1). This reduction in the number of moving parts may decrease size, cost, and complexity of the assembly 100.

[0128] Figure 10 shows an alternative switching assembly 200 in which the pins 130 of the embodiments 100 described with respect to the earlier figures are replaced with sliding pads 230. Corresponding reference numerals (incremented by 100) are used for corresponding features. As for the pins 130, the sliding pads 230 are rigidly coupled together to form a single movable body 250 actuated by a single actuator 252 in the implementation described below, although each sliding pad 230 could be separately movable, and optionally also separately actuated, in other implementations. A linear actuator 252 is again used in this example.

[0129] The switching assembly 200 of Figure 10 again is designed for a 3 -phase system with two phase fractions per phase, with the phases in a star configuration, and has four connectors 202a-d per phase. The first connector 202a is connected to a terminal of a first phase fraction N1 of the respective phase N, the second connector 202b is connected to the star point, the third connector 202c is connected to a terminal of the coil for the second phase fraction N2 of the respective phase N, and the fourth connector 202d is connected to an inverter input and to the other terminal of the first phase fraction N1 of the respective phase N. The terminal of the second phase fraction N2 of the respective phase N which is not connected to the third connector 202c is connected to the star point, and thereby to the second connector 202b. The connector arrangement is therefore equivalent to the connector arrangement of the earlier examples 100. In this example 200, as in the earlier examples 100, the phases are arranged in a star configuration, so the current path for each phase terminates at the star point inside the associated motor.

[0130] In Figures 10 to 14, only a part 201a of the housing of the fixed body 201 is shown - a plate 201b of the housing in front of the movable body 250 has been removed to allow the contacts to be seen. This plate 201b is shown in Figure 15, and is rigidly mounted on the back plate 201a to form a main structure of the fixed body 201. The connectors 202 are mounted on this plate 201b, as are various conducting links / busbars (as described below) which also form a part of the fixed body 201. Within the fixed body 201, which may be referred to as a terminal block 201, electrical connections o the switching assembly 200 are made - some of these connections are permanent, whereas others are movable / switchable, so allowing the electro-mechanical switching assembly 200 to function. Switchable connections are provided between pairs of contacts - one movable contact and one fixed contact.

[0131] The terminal block 201 comprises two fixed conductors 222 per phase, each in the form of a busbar 222 mounted on the fixed body 201. The first busbar 222a is permanently connected to the first connector 202a, and the second busbar 222c is permanently connected to the third connector 202c.

[0132] The switching assembly 200 comprises a movable body 250 slidably mounted within the terminal block 201. The movable body 250 comprises a plate 245 made of an insulating material, the plate 245 being arranged parallel to the plates 201a, 201b of the fixed body 201.

[0133] In the embodiment shown in Figure 10, the terminal block 201 and movable body 250 are both curved (e.g. to better fit on a circular stator of a motor) and perpendicular directions in the plane of each plate 201a, 201b, 245 are described as circumferential and radial accordingly. The busbars 222 are oriented at least substantially radially in the implementation being described, and the first and second connectors 102a, b are located adjacent to each other near a radially-inward side of the terminal block 201 whereas the third and fourth connectors 102c, d are located adjacent to each other near a radially -outward side of the terminal block 201. The first busbar 222a extends radially outward from the first connector 102a and the second busbar 222c extends radially inward from the third connector 202c, towards the second connector 202b.

[0134] The movable body 250 is arranged to move circumferentially with respect to the terminal block 201, along the length of the terminal block 201. It will be appreciated that the curvature is low relative to the displacement, and that a straight-line implementation would therefore be a trivial alternative.

[0135] The movable body 250 comprises three pads 230 for each phase, each pad 230 being elongate in shape and oriented at least substantially circumferentially / perpendicular to the busbars 222. The pads 230 are embedded in, or firmly mounted in place on, the plate 245 of the movable body 250 such that they move with / as part of the movable body 250. The pads 230 may each be in the form of a busbar - the word “pad” is used to reduce the risk of confusion with the fixed busbars 222.

[0136] The first pad 230a is located near the first and second connectors 202a, 202b, in particular being at or near the same radial position as the first and second connectors 202a, 202b, and is movable between a first position in which the first pad 230a is circumferentially offset from at least one of the first and second connectors 202a, 202b and a second position in which the first pad 230a contacts the first and second connectors 202a, 202b, so forming a conductive bridge directly between the two adjacent connectors.

[0137] The second pad 230d is located near the third and fourth connectors 202c, 202d, in particular being at or near the same radial position as the third and fourth connectors 202c, 202d, and is movable between a first position in which the second pad 203d is circumferentially offset from at least one of the third and fourth connectors 202c, 202d and a second position in which the second pad 230d contacts the third and fourth connectors 202c, 202d, so forming a conductive bridge directly between the two adjacent connectors.

[0138] In the figures showing images of this switching assembly 200, the first and second pads 230a, 230b are offset from both of the connectors 202 in the position in which the pad does not form a bridge between the pair of connectors 202. However, in the electrical schematics discussed below (Figures 16A and 16B) each pad 230a, 230b is still touching one fixed connector 224a, 224d in the first position, despite no current flowing therethrough (as the pad forms an electrical “dead end” with no onward path). This overlap - where present - may help to allow the apparatus 200 to remain compact.

[0139] The third pad 230c is located radially between the radial positions of the two pairs of connectors 202a-b, 202c-d (being in a middle region of the movable body 250), and is movable circumferentially between a first position in which the third pad 203c contacts both busbars 222, so forming a conductive bridge between the busbars and thereby between the first and third connectors 202a, 202c, and a second position in which the third pad 230c contacts only the second busbar 222b. In other implementations, the third pad 230c may not touch either of the connectors 202a, 202c in the second position.

[0140] The switching assembly 200 also comprises one further conductor 260 per phase, electrically connecting an inverter input connector (as marked A, B, C in Figure 11A) to the fourth connector 202d. In the implementations 100 described with respect to Figures 3 to 9, this pathway was instead provided by the fourth connector 102d itself, illustrating that the fixed conductors can simply act as extensions of the connectors 102, 202.

[0141] Figure 11A shows the switching assembly 200 with the movable body 250 in the first configuration, and Figure 11B shows the switching assembly 200 with the movable body 250 in the second configuration, with the unlabelled arrows indicating the direction of movement of the movable body 250 relative to the fixed body 201 between the two positions.

[0142] Figure 12 illustrates the current flow path in the first position of the movable body 250. Input from an inverter for phase A travels along the conductor 260 to the fourth connector 202d. The fourth connector 202d is an electrical “dead end” within the switching apparatus 200 in this position, so the current flows only to the coil forming the first phase fraction, Al, as that is the only available current path from the fourth connector 202d in the first position. The current flows through the coil Al and to the first connector 202a. From the first connector 202a, the current flows into the first busbar 222a which is permanently connected thereto, and then through a fixed contact of the first busbar 222a into the third pad 230c, and from the third pad 230c to the second busbar 222c through a fixed contact of the second busbar 222c. The third pad 230c provides a moving contact surface between the first and second busbars 222. From the second busbar 222c, current flows to the third connector 202c which is permanently connected thereto, and from the third connector 202c to the coil forming the second phase fraction, A2. After passing through the second coil A2, the current flows on to the star point.

[0143] This first electrical configuration may therefore be referred to as a series configuration, as current passes through each coil Al, A2 of the phase A in turn. The electrical schematic for this is shown in Figure 16A, which is discussed in more detail below.

[0144] Figure 13 illustrates the current flow path in the second position of the movable body 250. Input from an inverter for phase A travels along the conductor 260 to the fourth connector 202d. The fourth connector 202d offers a current path within the switching apparatus 200 in this position, as well as being connected to the coil forming the first phase fraction, Al. The current flow therefore splits.

[0145] A first portion of the current flows through the coil Al and to the first connector 202a. From the first connector 202a, the first busbar 222a which is permanently connected thereto is an electrical “deadend” in this position, unlike in the first position, so the current instead flows through the pad 230a to the second connector 202b (which was unused in the first position), as the pad 230a is positioned to form a conductive bridge between these connectors 202a, b in this position. From the second connector 202b, current flows on to the star point. Simultaneously, a second portion of the current flows from the fourth connector 202d along the pad 230d and to the third connector 202c, as the pad 230d is positioned to form a conductive bridge between these connectors 202c, d in this position. From the third connector 202c, current flows through the coil forming the second phase fraction, A2, and from there to the star point.

[0146] This second electrical configuration may therefore be referred to as a parallel configuration, as current splits, so that only a portion passes through each coil Al, A2 of the phase A, before the current portions rejoin at the star point. The electrical schematic for this is shown in Figure 16B, which is discussed in more detail below.

[0147] The first pad 230a and second pad 230d therefore each provide a contact surface linking a pair of connectors 202 in the second position (parallel configuration). The pads 230 are movable, and these connections are not available in the first position (series configuration). The pads 230 may also be referred to as patch busbars 230.

[0148] In the first, series, position the switching assembly 200 makes use of one movable pad 230c, which makes contact with two fixed contacts 222a, 222c - one being provided by each of the fixed busbars 222. A total of either three or four contacts is therefore used per phase, depending on whether the pad 230c is counted as two linked movable contacts or as a single movable contact. In the second, parallel, position the switching assembly 200 use of a different two movable pads 230a, 230d. A total of either six or eight contacts is therefore used per phase, depending on whether each pad 230a, 230d is counted as two linked movable contacts or as a single movable contact. The switching assembly 200 has a total of six stationary contacts - two provided by the busbars 222a, 222c, and four provided by the connectors 202a-d. It will be appreciated that the busbars 222a, 222c each effectively provide an extension to the connector 202a, 202c to which that busbar 222 is permanently attached, so providing a second contact in a different location for the same connector 202. This may be thought of as two of the four connectors per phase offering only a single fixed contact, and the other two of the four connectors per phase offering two fixed contacts in different locations, for ease of forming different current paths in the fixed body 201. Although the same busbar 222 may provide both fixed contacts for its connector 202 in some implementations, so having a single surface providing both contacts, this busbar surface is locked in position with respect to the connector 222 so the connections each have a fixed position rather than being movable across the surface, unlike for the pads 230. The switching assembly 200 therefore uses a total of 9 or 12 contact surfaces per phase, depending on whether the three pads 230 are each classed as providing a single contact surface, or a pair of contacts.

[0149] In the electrical schematics (Figures 16A and 16B) input from an inverter for each phase (A, B, C) marked by the corresponding letter within an arrow. For the first phase (A) only, arrows are used to indicate the direction of current flow, and unused conductive paths are shown in grey whereas conductive paths along which current is flowing are shown in black. The same applies to the later phases but the current flow and path usage is not marked, for clarity. For the second phase only (B) reference numbers are marked for the fixed and movable contacts. A dashed line is used to indicate the rigid coupling of the movable components 230a, d,c, 245 which together form the movable body 250, with a double-headed arrow indicating the movement of the movable body 250 between the first and second positions.

[0150] As can be seen from comparing Figures 16A and 16B, four fixed contacts (the fixed contact 224d of connector 202d to the corresponding movable pad 230d, the fixed contact 224c of connector 202c to the same movable pad 230d, the fixed contact 224b of connector 202b to the corresponding movable pad 230a, and the fixed contact 224a of connector 202a to the same movable pad 230a) are unused in the series configuration, and one of the connectors 202b is completely unused. Only two of the fixed contacts - those to the movable pad 230c - are used in the series configuration.

[0151] By contrast, in the parallel configuration all four fixed contacts 224a-d listed as unused in the series configuration are used, and the two fixed contacts 224a’, 224c’ used in the series configuration are not used - a completely different set of fixed contacts is therefore used for each position in this implementation. The current path within the fixed body 101 is therefore different between the two configurations. Similarly, the current path within the movable body 250 is different between the two configurations - just one pad 230c (circled in dark grey in Figure 14) has current flowing through it in the series configuration, whereas only the two other pads 230a, 230d (circled in light grey in Figure 14) have current flowing through them in the parallel configuration.

[0152] Each busbar 222 provides a conductive contact surface facing the pads 230 - this contact surface 224 does not move with respect to the fixed body 201, and so is described as a fixed contact. Any point at which the contact surface 224 touched the pad 230 as the pad moves across it can serve as a contact point / region, such that sliding conductive contact is provided across at least substantially all of this surface 224 (as for the surface of the pin head 331 and the surface of the pin’s sleeve 133 in the implementations 100 described above). A single surface 224 provides a fixed contact for two pads 230. In other implementations, however, the busbar 222 could be replaced with a pair of separate fixed contacts 224, connected by a conductor of a different form (e.g. a wire, or insulated metal strip of any shape). However, it will be appreciated that use of a single busbar 222 may help to reduce system size, cost, and / or complexity, and may improve reliability.

[0153] As for the example 100 described above, this switching assembly 200 uses sliding contacts, however in this case they are flat pads 230 which bridge between different busbars 222. In the implementation being described, the pads 230 are spring-loaded as shown in Figure 15 (in this example, by two coil springs 232, although any suitable biasing means may be used), and thereby biased towards the busbars 222. The springs 232 are located between the pad 230 and a plate 245 of the movable body 250, pushing the pad 230 upwards in the orientation shown (out of the plane of the movable body plate 245). This biasing force is therefore perpendicular to the direction of sliding of the movable housing 250. The biasing means 232 ensures a positive contact force over each connection, which both ensures that firm contact is made with the fixed contacts so as to provide good electrical conductivity, and potentially also increases friction so reducing the likelihood of the movable body 250 slipping with respect to the terminal block 201.

[0154] In the implementations 100, 200 described above, the switching assembly 100, 200 has a first position, in which the phases are arranged in a series electrical configuration, and a second position, in which the phases are arranged in a parallel electrical configuration. Sliding movement of the pins 130 or pads 230 provides the movement between the first and second positions.

[0155] In the implementations 100, 200 described above, each sliding contact surface (pin sleeve 131 or pad 230) may be always in contact with at least one fixed contact 124, 224, even if that contact is not live / if no current is flowing through that contact in that position. Allowing the sliding surface to remain in contact in this way may facilitate producing a more compact switching assembly as the movement distance required for the sliding surface is lower than if it were required to move clear of both contacts when unused), and may facilitate maintaining alignment.

[0156] Figure 17 shows an alternative switching assembly 300 in which the sliding pins 130 or pads 230 of the embodiments 100, 200 described with respect to the earlier figures are replaced with non-sliding contacts. Corresponding reference numerals (incremented by 100) are used for corresponding features. As for the pins 130 and pads 230, the movable parts 330 of this implementation 300 are rigidly coupled together to form a single movable body 350 actuated by a single actuator 352 in the implementation described below, although each movable part 330, 330’ could be separately movable, and optionally also separately actuated, in other implementations.

[0157] The switching assembly 300 of Figure 17 again is designed for a 3-phase system with two phase fractions per phase and the phases in a star configuration, and has four connectors 302a-d per phase.

[0158] The first connector 302a is connected to a terminal of a first phase fraction N1 of the respective phase N, the second connector 302b is connected to the star point between phases, the third connector 302c is connected to a terminal of the coil for the second phase fraction N2 of the respective phase N, and the fourth connector 302d is connected to an inverter input and to the other terminal of the first phase fraction N1 of the respective phase N. The terminal of the second phase fraction N2 of the respective phase N which is not connected to the third connector 302c is connected to the star point and thereby to the second connector 302b. The connector arrangement is therefore the same as the connector arrangement of the examples 100, 200 of Figures 3 and 10. In this example 300, as in the earlier examples 100, 200, the phases are arranged in a star configuration, so the current path for each phase terminates at the star point inside the associated motor. Each group of four connectors 302a-d is again arranged as a square of adjacent connectors of the terminal block 302 in this implementation.

[0159] The terminal block 301 of this switching assembly 300 comprises a base plate 301b below the rest of the switching assembly 300 and an insulating support 301a for the set of connectors 302, which again take the form of terminal connector sockets 302 in this implementation, but could be provided as pins in other implementations. A housing 301c surrounds the switching assembly components and connects the base plate 301b to the insulating support 301a, which is in an upper region of the terminal block 301 in the examples pictured. In some implementations, the housing 301c and / or base plate 310b may be made of an insulating material. In the implementation being described, however, the housing 301c, and optionally also the base plate 301b, is made of metal for electrical shielding purposes - an insulating layer or coating may be provided to electrically isolate the housing 301a,b from the conductors 322 etc., although a gap (e.g. an air gap, or a space filled with a dielectric oil) may be deemed sufficient in some implementations.

[0160] A corresponding conductor 322a-d permanently connected to each respective connector 302a-d extends downwardly from the connector 302a-d, towards the base plate 301b. Each conductor 322a-d is in the form of a metal strip, or busbar, in the example shown. In the implementation 300 pictured, the conductors 322a-d do not reach the base plate 301b, but are supported by other parts of the terminal block

[0161] 301 (in other implementations, the conductors 322a-d may reach the base plate 301b). It will be appreciated that these conductors 322 each effectively provide an extension to the connector 302 to which that conductor 322 is permanently attached, so as to provide fixed contacts in more convenient locations for the switching assembly 300. It will be appreciated that a differently-shaped connector 302 may remove the need for a separate conductor, with that role instead being performed by a part of the connector

[0162] 302 itself.

[0163] Each conductor 322 is substantially S-shaped in the implementation shown; curving outwardly away from the connector 302 and away from a centre-line of the terminal block 301, then downwardly and inwardly towards the facing conductor, before curving outwardly again nearer to the base plate 301b. The conductors 322 and base plate 301 therefore define a substantially enclosed space within the switching assembly 300. The movable body 350 is located within this substantially enclosed space. S-shaped busbars are easy to manufacture, and can provide the conductors 322. Advantageously, the S-shape allows for contacts from the same conductor 322 to be made in different places, spaced apart enough for one or more movable bodies or other assembly components to be suitably arranged around them, and may also provide angled contact surfaces (e.g. at an angle of up to 60° to the horizontal, in the orientation shown) for touching the movable contacts, so providing a larger contact area and / or more reliable contact. It will be appreciated that differently-shaped conductors 322, e.g. with an E-shaped section with different prongs of the “E” providing different fixed contacts, may be used in other implementations, optionally with flat contact surfaces.

[0164] The movable body 350 comprises two main parts 330, 330’, each providing a conductive path; these may be referred to as first and second conductive movable parts 330, 330’. The first conductive movable part 330 is arranged to move linearly so as to make and break contact between a pair of conductors 322, and the second conductive movable part 330’ is arranged to move linearly so as to make and break contact between a different pair of conductors. One conductor may be common to both pairs of conductors, optionally via a different-located fixed contact on that conductor. In the implementation pictured, both conductive movable parts 330, 330’ are at least substantially surrounded by the shaped conductors 322 - the shaped conductors 322 therefore define a space for the movable bodies 330, 330’ and provide fixed contacts for the movable bodies. The shaped conductors 322 may therefore provide at least the majority of a housing for the movable parts 330, 330’, which may reduce a risk of damage to them.

[0165] The first movable part 330 is located adjacent to the base plate 301 and comprises a central insulating portion 331 extending across the base plate 301 between an opposing pair of conductors 322a, b. The first movable part 330 is biased upwardly, towards the connectors 302a, b; in this implementation, the first movable part 330 is spring-loaded by a pair of coil springs 332a, 332b, one near the first conductor 322a and one near the second conductor 332b, to provide this biasing, so as to keep the first movable part 330 level (horizontal in the orientation shown).

[0166] A busbar 333 is mounted to one end of the central insulating portion 331. The busbar 333 extends between the first conductor 322a and the third conductor 322c, which is adjacent to the first conductor along that side of the switching assembly 300. As a busbar 333 is provided at one end of the first movable part 330 only, it will be appreciated that a smaller movable part 330 could be used, extending less of the distance between an opposing pair of conductors 322a, b. However, the extra length may assist in keeping the first movable part 330 level when actuated ss described below. The first movable part 330 is movable such that contact between the busbar 333 and the conductors 322a,c can be made (as shown in Figure 18 A) and broken (as shown in Figure 18B), so changing the available current pathways. Within each group of four connectors 302a-d, this busbar 333 is therefore arranged to provide a conductive bridge between one pair of adjacent connectors along one side of the switching assembly.

[0167] The busbar 333 is angled so as to face an underside of the respective conductors 322 as the conductors curve outwardly (in a lower portion of the S-shape). This angle may allow for a larger contact surface for the same conductor cross-section than if the conductors 322 were vertical and the busbar 333 contacting a lower end face of each. The busbar 333 therefore provides a movable contact surface, and each conductor 322a, c arranged to make contact therewith provides a fixed contact 324 which the busbar 333 touches in one of the two positions.

[0168] In the implementation shown, the first movable part 330 is arranged to be moved by a cam 353 of a rotary actuator 352. A rotating shaft 354 extends along the length of the switching assembly 300 within the substantially enclosed space (in a narrower region thereof, near the inward bends of the S-shaped conductors 322 in this example) and comprises one cam 353 for each facing pair of connectors 302. The cam 353 for the first pair of connectors 302a, b is arranged to push the first movable part 330 downwards, against the biasing springs 332, over a first part of the shaft’s rotation, so breaking contact between the busbar 333 and the conductors 322a, c. The first movable part 330 is then released to move upwards over a second part of the shaft’s rotation, so re-making the electrical contact under the influence of the springs 332. The first movable part 330 comprises a protrusion 334 shaped to interact with the cam 353 in the implementation shown, although the cam 353 may push against a differently-shaped surface in other implementations. The protrusion 334 may be made of a different - optionally conductive - material from the material of the central insulating portion 331. The material may be selected to be harder-wearing, due to repeated expected contact with the cam 253 (metal is chosen in the implementation being described), and / or to provide better grip on the cam 253.

[0169] Although the cam 353 serves to push the first movable part 330 downwards, the motion of the surface of the shaft 354 adjacent to the first movable part 330 is at least substantially horizontal, so approximately perpendicular to the springs’ biasing force. As such, the spring force against the cam 353 will not cause the cam 353 to slip even when the actuator 252 is unpowered - as for the earlier two examples 200, 300, there is therefore no need for the actuator 152, 252, 352 to be continuously powered; it can simply be switched on when a change in position is wanted, and switched off again once that movement is complete. Similarly, no locking mechanism is required to hold the movable bodies 150, 250, 350 in place.

[0170] The second movable part 330’ is located further from the base plate 301 / above the first moving part 330, and comprises a conductive plate 330a’ extending between the opposing pair of conductors 322a, b. These conductive plates 330’ are therefore arranged to provide a conductive bridge between opposite connectors which face each other across a width of the switching assembly 300. Within each group of four connectors 302a-d, two such conductive plates 330’ are provided; one 330a’ linking the first and second conductors 322a, b, and the second conductive plate 330d’ (not visible in the figures, except the electrical schematic) linking the third and fourth conductors 322c, 322d. The second cam - not visible in the figures - is arranged to interact with the second conductive plate 330d’ which extends between the third and fourth conductors 322c, d, and with the first movable part 330c for the third and fourth conductors 322c, d - the first movable parts 330a, c are rigidly coupled together by a busbar 333 at one end and a non-conducting bar at the other end, in the implementation shown. The use of two synchronised cams 253 on the same shaft 254 to push this may help to keep the movable part 330 level.

[0171] The second movable part 330’ is biased downwardly, towards the cam 253 and towards the base plate 301; in this implementation, the second movable part 330’ is spring-loaded by a pair of coil springs 332a’, 332b’, one near the first conductor 322a and one near the second conductor 322b, to provide this biasing, so as to keep the second movable part 330’ level (horizontal in the orientation shown). The biasing means 332a’, 332b’ are mounted between an upper side of the second movable part 330’ and a lower side of the insulating supports 301a which holds the terminal points / connectors 302, and arranged to provide a downward biasing force on the second movable part 330’.

[0172] The second movable part 330’ has angled sides so as to face an upper side of the respective conductors 322 as the conductors curve inwardly towards the shaft 254 (in an upper portion of the S- shape). This angle may allow for a larger contact surface for the same conductor and plate cross-section. The conductive plate 330’ therefore provides a pair of movable contacts 335’, one for each conductor 322, and each conductor 322 provides a fixed contact 324’ with which one contact 335’ of the conductive plate 330’ makes contact. For the first conductor 322a, the corresponding movable contact 335a’ of the movable part 330’ is arranged to make and break contact with the respective fixed contact 324a’. For the second conductor 322b, the corresponding movable contact 335b’ of the movable part 330’ is arranged to make and break contact with the respective fixed contact 324b’. The movable part 330’ moves vertically under the influence of the rotating cam 253 - the cam 253 pushes the second movable part 330’ upwards, and the second movable part 330’ returns downward under the influence of the biasing means 332’ as the cam 253 rotates away from the second movable part 330’.

[0173] Both movable parts 330, 330’ are therefore biased towards the shaft 354 in this implementation, by respective biasing means 332a, b, a’, b’. The second movable part 330’ is arranged to be moved by the same cam 253 as moves the first movable part 330. This cam 353 is arranged to push the second movable part 330’ upwards, against the biasing springs 332’, over a second part of the shaft’s rotation, so breaking contact between the conductive plate 330’ and the conductors 322. The second movable part 330’ is then released to move downwards over the first part of the shaft’s rotation, so re-making the electrical contact under the influence of the springs 332’. The second movable part 330’ comprises a protrusion 334’ shaped to interact with the cam 353 in the implementation shown, although the cam 353 may push against a differently-shaped surface in other implementations. The protrusion 334’ may be made of a different material from the conductive plate 330’, although it is made of the same metal in the implementation being described. The material may be selected to be harder-wearing, due to repeated expected contact with the cam 253, and / or to provide better grip on the cam 253.

[0174] The actuator 352 of this implementation 300 therefore comprises a rotating part (the shaft 354) with a cam 353 mounted thereon. The rotating part 354 and cam 353 lie between the first movable part 330 and the second movable part 330’, such that the cam 353 pushes the first movable 330 part in a first direction over a first angular range of rotation of the shaft 354, and the second movable part 330’ in a second direction opposite to the first direction over a second angular range of rotation of the shaft 354. The first and second directions are both vertical in the orientation shown. The cam 353 interacts with the first movable part 330 beneath the shaft 354. The lowest point on an underside of the shaft 354 moves horizontally (leftward for clockwise rotation; rightward for anticlockwise rotation) at the point at which the cam 353 is lowest; the cam’s direction of movement is therefore at least substantially perpendicular to the biasing direction of the first movable 330 part - the cam 353 is not free to move vertically upwards, so even if the actuator 352 is powered off, the first movable 330 part will not push the cam 353 out of place. The same applies for the second movable part 330’ above the shaft 354.

[0175] The movable body 350 is arranged to move vertically (in the orientation shown) between a first position as shown in Figure 18A, and a second position as shown in Figure 18B, under the influence of a rotary actuator 352. In the first position, the cam 253 is in its highest position, and the movable body 350 is correspondingly in its highest position, with the first movable part 330 pressing against the contacts 324 of the conductors 322 above it, and the second movable part 330’ lifted above the contacts 324’ of the conductors 322. The movable body 350 therefore provides a bridge between pairs of adjacent conductors 322, but not between pairs of opposing conductors, in this position. Figure 19 illustrates the current flow path in this position. In the second position, the cam 253 is in its lowest position, and the movable body 350 is correspondingly in its lowest position, with the first movable part 330 pushed downwardly away from the conductors 322 above it, and the second movable part 330’ pressing against the contacts 324’ of the conductors 322 below it. The movable body 350 therefore provides a bridge between an opposing pairs of conductors 322a, b, but not between pairs of adjacent conductors, in this position. Figure 20 illustrates the current flow path in this position.

[0176] As shown in Figure 19, in the first position of the switching apparatus 300 input from the inverter is received at the fourth connector 302d. As the conductive plate 330’ is not in contact with the conductor 322d in this position, no current flow paths from the fourth connector 302d are available within the switching apparatus 300, so the current flows only to the first coil Al of the phase A. After leaving the coil Al, the current flows to the first connector 302a, down through the corresponding conductor 322a, and into the busbar 333 as the movable busbar 333 is touching the fixed contact 324a in this position. Current then flows along the busbar 333 to the third conductor 322c, via the fixed contact 324c of the third conductor which is touching the busbar 333, up the third conductor to the third connector 302c and from there to the second coil A2 of the phase. The current passes through the coil A2 before reaching the junction (star) point between phases. The electrical configuration in this position is therefore a series configuration, as all of the current passes through both coils, one after the other. The electrical schematic for this is shown in Figure 22A, which is discussed in more detail below.

[0177] As shown in Figure 20, in the second position of the switching apparatus 300 input from the inverter is again received at the fourth connector 302d. In this second position, the second movable body 330’ is in contact with the conductor 322d extending away from the fourth connector 302d so a current path is provided within the switching apparatus 300 as well as the current flow to the first coil Al of the phase A. The current flow therefore splits.

[0178] A first portion of the current flows through the coil Al and to the first connector 302a. From the first connector 302a, the current flows downwardly along the first conductor 322a - the movable plate 330a’ is positioned to form a conductive bridge between the first conductor 322a and the second conductor 322b in this position, so current flows through the second movable part 330’ to the second conductor 322b, and up through the second conductor 322b to the second connector 302b. From the second connector 302b, current flows on to the star point. The busbar 333 is not touching the first conductor 322a in this position, so the lower portion of the first conductor is an electrical “dead-end” in this position, unlike in the first position. Simultaneously, a second portion of the current flows from the fourth connector 302d, down through the fourth conductor 322d, along the second movable plate 330d’, to the third conductor 322c, and on to the third connector 302c, as the second movable plate 330d’is positioned to form a conductive bridge between these connectors 302c, d in this position. From the third connector 302c, current flows through the coil forming the second phase fraction, A2, and from there to the star point. This second electrical configuration may therefore be referred to as a parallel configuration, as current splits, so that only a portion passes through each coil Al, A2 of the phase A, before the current portions rejoin at the star point. The electrical schematic for this is shown in Figure 22B, which is discussed in more detail below.

[0179] The switching assembly 300 therefore again provides series-parallel switching. The two movable plates 330a’, 330d’ each provide a contact surface linking a pair of facing connectors 202 in the second position (parallel configuration). The plates 330’ are movable, and this connection is not available in the first position (series configuration). The busbar 333 provides a contact surface linking a single pair of adjacent connectors 202 in the first position (series configuration). The busbar 333 is movable, and this connection is not available in the second position (parallel configuration).

[0180] This switching assembly 300 does not use sliding contacts; although the movable body 350 still moves linearly between two positions, the movable contacts are moved away from a plane including the corresponding fixed contacts, instead of sliding along that plane. The movable body 350 of this implementation is actuated by a cam 253 which rotates to push the moving parts up / down. In each position, a suitable current path is provided for the corresponding electrical configuration. In one position, connectors 302 are linked to those opposite, whereas in the other position connectors 302 are linked to those adjacent.

[0181] As in the electrical schematics discussed above, in Figures 22A and 22B input from an inverter for each phase (A, B, C) is marked by the corresponding letter within an arrow. For the first phase (A) only, arrows are used to indicate the direction of current flow, and unused conductive paths are shown in grey whereas conductive paths along which current is flowing are shown in black. The same applies to the later phases but the current flow and path usage is not marked, for clarity. For the second phase only (B) reference numbers are marked for the fixed and movable contacts. A dashed line is used to indicate the rigid coupling of the movable components 330, 330a’, 330d’ which together form the movable body 350, with a double-headed arrow indicating the movement of the movable body 350 between the first and second positions.

[0182] As can be seen from comparing Figures 22A and 22B, four fixed contacts (the pairs of fixed contacts 324’ to the movable plates 330a’, 330d’) are unused in the series configuration, and one of the connectors 302b is completely unused. Only two of the fixed contacts 324a, 324c - those to busbar 333 of the first movable part 330 - are used in the series configuration. By contrast, in the parallel configuration this is reversed - all four fixed contacts 324’ unused in the series configuration are used, and the two fixed contacts 324a, 324c used in the series configuration are not used - a completely different set of fixed contacts is therefore used for each position in this implementation. The current path within the fixed body 301 is therefore different between the two configurations. Similarly, the current path within the movable body 350 is different between the two configurations: just the busbar 333 has current flowing through it in the series configuration, whereas only the two movable plates 330a’, 330d’ have current flowing through them in the parallel configuration.

[0183] In the first, series, position the switching assembly 300 therefore makes use of one patch busbar 333 (for a total of either three or four contacts per phase, depending on whether the busbar 333 is classed as a single contact surface or a pair of coplanar contacts). In the second, parallel, position the switching assembly 300 makes use of a different two patching busbars - the movable plates 330a’, 330d’ (for a total of eight contacts per phase). The switching assembly 300 therefore uses a total of eleven or twelve contact surfaces per phase, depending on definition.

[0184] In this switching assembly 300, the insulating components 301a, b,c of the terminal block 301 may be connected together so as to be at least substantially fluid-tight, or sealed, such that the assembly 300 can be flooded with a dielectric oil. Such a non-conducting oil can serve as both lubricant and coolant - lubricating the moving parts (reducing wear), whilst also transporting heat away from hot-spots within the assembly 300. The dielectric oil may serve to transport heat to the housing 301a-c and thereby to the outside environment, or optionally to transfer the heat to a circulating fluid cooling system such as one which may be used to cool the motor. A dielectric oil may be used in a similar manner for any of the other switching assemblies 100, 200 described herein.

[0185] The implementations 100, 200, 300 above all illustrate series-parallel switching in a star configuration. However, it will be appreciated that the same principles can be used for delta configurations, and indeed for switching assemblies arranged to switch between different electrical configurations, and indeed between different numbers of electrical configurations. Figures 23 and 24 illustrate electrical schematics for delta-star switching (two different configurations) and for delta-starseries-parallel switching (four different configurations). The schematics provided are for sliding pin-type implementations as discussed above with respect to Figures 4 A and 4B.

[0186] Figure 23 shows electrical schematics for a switching assembly 400 using sliding pins 430, similar to those used in the implementation of Figures 3 to 8, but with the circuitry configured to provide deltastar switching instead of series-parallel switching. Figure 23A shows this in a first position corresponding to a star configuration, and Figure 23B shows this in a second position corresponding to a delta configuration. The movable body 450 comprises just one sliding pin 430, which always forms an electrical contact with one first fixed contact 424a, but selects between bridging to the second fixed contact 424b or the third fixed contact 424c between the two different positions. The three fixed contacts 424a-c (for each phase A, B, C) are arranged in a straight line parallel to, and immediately adjacent to, the sliding pin 430. Sliding the pin 430 along that line determines which pair of fixed contacts are bridged between - the contact surface of the pin 430 is arranged to be too short to touch all three fixed contacts 424 simultaneously, so reducing a risk of short circuits.

[0187] This sliding pin 430 has just one contact surface, like the sleeve 133 discussed for the sliding pin 130 of the implementation of Figures 3 to 9, and does not offer a second current path. This one contact surface is always in use for each pin 430 in this implementation. Just one pin is used per phase to provide star-delta switching in this design. The surface of the pin 430 slides along a surface including the fixed contacts 424. As described above for the first implementation 100, this sliding pin 430 may have a constant width along its length (at least for a portion of its length greater than its movement distance), so as to provide continual, smooth, sliding, contact with the fixed contacts 424 throughout operation. The fixed contacts 424 may be biased towards the movable, sliding, contact surface, with the biasing force optionally being perpendicular to the contact surface. In the implementation shown, the pin’s contact surface remains in contact with the central fixed contact 424a of the straight line, and selects the left 424b or right 424c fixed contact to be joined to that central fixed contact 424a by sliding of the pin along that straight line. Provision of a sliding contact, rather than e.g. a hinged switch, may allow for a more compact design, so reducing space taken by the assembly. In addition, the use of a sliding contact surface facing the fixed contacts may improve reliability and lifespan, as precise alignment of the movable contact 430 is not needed for a strong connection - anywhere on the conductive sliding surface can act as the movable contact. Further, the fixed contacts 424 can be biased towards the conductive sliding surface of the pin 430 to improve electrical contact without interfering with the pin’s sliding action or requiring a locking mechanism, as the biasing direction can be perpendicular to the direction of sliding. The biasing mechanism (e.g. one or more coil springs) therefore does not act against the actuator / against the movement of the pin, so no locking mechanism may be needed to hold the pin in place, and the actuator may not be continually -powered (as the pin 430 is naturally held in place, without positive action). Indeed, this biasing mechanism may actually improve grip of the pin 430 in its desired position by increasing friction. In some implementations, the biasing of contacts may not be perpendicular to the actuator movement direction, whilst still being in a direction different from that of the actuator’s movement - e.g. springs may provide a biasing force at an angle of around 60° to the movement of an actuator. In such implementations, a component of the spring force may therefore be along the actuator movement direction, but the other component of the spring force is perpendicular to the actuator movement direction - the increased friction provided by this perpendicular component may more than compensate for the component of the force in the actuator movement direction. In Figure 23, a single coil Al, B l, Cl is shown per phase. However, this is illustrative only and the phases could have any number of coils, in series or in parallel, without affecting the delta-star configuration between the phases.

[0188] In the first position, the star configuration, one fixed contact 424c is unused. The pin 430 forms a bridge between the other two fixed contacts 424a, 424b, leaving 424c as an electrical dead-end. In this configuration, the rail 490 representing the joining of phases at the star point 490 is used / is a part of the current path. By contrast in the second position, the delta configuration, that fixed contact 424c is connected to the first fixed contact 424a by the pin 430, and it is the second fixed contact 424b that is unused. In this configuration, the rail representing the joining of phases at the star point is unused / is not a part of the current path, and instead fixed connections 495 provide a link (junction point) from phase A to phase B (unlike the star point which connects all three - or more- phases in star configurations, these connections 495 and junction points just connect one phase to an adjacent phase, so effectively forming a loop; the triangular shape of this loop for a 3 -phase system is what gives this configuration the name delta (A), as opposed to the star shape of the star configuration, with all phases radiating outwardly form a single point), and from phase B to phase C. Fixed contacts 424c provide this current path to the adjacent phase, linking phase A to phase B, phase B to phase C, and phase C back to phase A, completing the loop. The current flow path within the fixed body 401 is therefore different between the two positions, whilst current flows along the same contact surface of the pin 430 in both positions. In other implementations, for example as described below with respect to Figure 33, the current flow path within the movable body 450 may also differ between the different positions in delta-star switching.

[0189] Figure 24 shows electrical schematics for a switching assembly 500 using sliding pins as for Figures 3 to 8, but with the circuitry configured to provide both delta-star switching and series-parallel switching. This switching assembly 500 may be thought of as a combination of the switching assembly 100 described with respect to Figures 3 to 9 and the switching assembly 400 described with respect to Figure 23. Figure 24A shows this in a first position corresponding to a series-star configuration; Figure 24B shows this in a second position corresponding to a parallel-star configuration; Figure 24C shows this in a third position corresponding to a series-delta configuration; and Figure 24D shows this in a fourth position corresponding to a parallel-delta configuration. In this switching assembly 500, two separate movable bodies 150, 450 are provided. The first movable body 150 is for series-parallel switching, and the second movable body 450 is for star-delta switching. The movable bodies 150, 450 are separately- actuated in this implementation 500 to allow one to be moved without the other being moved when desired, e.g. when a series-parallel switch is wanted whilst retaining the phases in a star arrangement. A single actuator may be used to move both movable bodies 150, 450 in some implementations. The first movable body 150 comprises two sliding pins 130 per phase, each offering two conductive paths, and is as described with respect to Figures 3 to 9. The second movable body 450 comprises just one sliding pin per phase, each with just one conductive path, and is as described with respect to Figure 23.

[0190] In Figure 24, two coils Al, A2 are shown per phase. However, this is illustrative only and the phases could have any number of coils. The number of pins 130 of the first movable body 150 would be scaled accordingly for additional coils, whereas the second movable body 450 would be unaffected. In the first position, the series-star configuration, three fixed contacts 124b, 124d, 424c are unused. By contrast in the second position, the parallel-star configuration, the fixed contact 424c of the delta-star part of the switching mechanism 500 remains unused, but the two fixed contacts 124d, 424c of the series-parallel part of the switching mechanism 500 are used. In the third and fourth positions, fixed contact 424c of the delta-star part of the switching mechanism 500 is used, and fixed contact 424b of the delta-star part of the switching mechanism 500 is unused instead (the remaining fixed contact 424a of the delta-star part of the switching mechanism 500 is used in all four configurations). In the third position, the series-delta configuration, three fixed contacts 124b, 124d, 424b are unused (124d being unused in terms of current flow paths within the terminal block 501 but optionally still providing a current path from the inverter to a coil). By contrast, in the fourth position, the parallel-delta configuration, fixed contact 424b of the deltastar part of the switching mechanism 500 is the only unused fixed contact. The current flow path within the fixed body 501 is therefore different between each of the four positions, whilst the current flow path in the movable bodies 150, 450 changes when a series-parallel switch is made, but not when a delta-star only switch is made (as the same contact surface of the corresponding moving body 450 is used).

[0191] In all of the assemblies 100, 200, 300, 400, 500 described above, at least one movable contact of the movable body 150, 250, 350, 450 is in the form of a contact surface, the contact surface being arranged to touch two fixed contacts so as to provide a current path directly between the two fixed contacts in at least one of the first configuration and the second configuration. For the pin-based first switching assembly 100, this contact surface is provided by the sleeve 133 of each pin, which provides a conductive bridge between two fixed contacts 124b, 124d in the parallel configuration only. For the sliding pad-based second switching assembly 200, such a contact surface is provided by each sliding pad 230 as each of these 230 bridges between two fixed contacts 124 in one of the series configuration and the parallel configuration. For the rotary actuator-based third switching assembly 300, this contact surface is provided by the movable busbar 330, which provides a conductive bridge between two fixed contacts 124b, 124d in the parallel configuration only. In all of these examples, the contact surface is continuous and exposed across at least a majority of the surface such that an electrically-conductive connection could be made at any point across at least a majority of the surface. In all of these examples, the plane of the contact surface 133, 230 includes a straight line between the fixed contacts between which it provides a bridge when the fixed and movable contacts are touching, and the straight line between the fixed contacts is parallel to the contact surface even when the contacts are not touching. Any imperfect alignment between the fixed and movable contacts may be accommodated, as the fixed contacts may touch any part of the movable contact surface to provide a functional connection. In all of these examples, the movement of the movable contact surface is along a straight line towards the fixed contacts. In the first two examples 100, 200, the movement is sliding movement parallel to / along the contact surface 133, 230; in the third example 300, the movement is perpendicular to / towards the contact surface 330. In the second two examples 200, 300, the contact surface is a flat, planar surface, although curved surfaces could be used provided the fixed and movable bodies are provided with complementary curved surfaces. In implementations with such a contact surface (whether or not the surface is a sliding contact surface), cost and / or size of the apparatus may be reduced, and reliability may be increased due to a reduction in number of interconnections. In other implementations, however, this continuous contact surface 133, 230, 330 may be replaced by a pair of contacts connected by any suitable conductor.

[0192] It will be appreciated that the particular embodiments described in detail herein are provided by way of example only, and are not intended to limit the scope of the claims. Many possible variations will be apparent to the skilled person on reading this disclosure. For example, Figures 25 to 32 illustrate an implementation using a similar arrangement to that described with respect to Figures 2 to 9, but with various differences as outlined below. The description below focuses on the differences; this implementation 600 works generally as described with respect to Figures 3 to 9, excepting these differences.

[0193] In this switching assembly 600, the terminal sockets 102 used as connectors 102 in the terminal block 101 of the earlier example 100 are replaced with terminal pins 602 which pass at least substantially through the terminal block 601, offering a male connection on each side of the terminal block 601. As in the implementation 100 described above, there are twelve connectors 602 provided for a 3-phase motor with two phase fractions per phase. These connectors 602 are again provided in two rows of six connectors, but these rows are curved instead of straight (as can be seen most clearly in Figures 28 and 29). An inverter input connection 620 is provided for each phase (A, B, C) - the inverter input connection 620 being provided on an opposite side of the switching assembly 600 from the mounting to the motor (discussed below). The inverter input connection 620 may therefore be provided on one end of the pin 602d which provides the connector 602d (as shown in Figure 25, which is a cross-section through a middle of the actuator 652), whist the other end of the pin 602d is connected to the motor (and in particular to an end of a first coil B l of the respective phase B of that inverter input, for this implementation). The inverter input connection 620 may be in the form of a socket, with an inverter connector plug 622 being arranged to be connected thereto, as shown in Figure 31, when the apparatus is powered.

[0194] In addition to the change in terminal connector design 602, internal details of the switching mechanism have also been adjusted in this implementation 600, whilst maintaining electrical connections corresponding to the schematics shown in Figures 9A and 9B. In particular, the busbars 645 joining adjacent pairs of sliding pins 630 have been relocated to join heads 631 of pins 630, rather than pin tips. The sliding pins 630 have been reconfigured accordingly such that, instead of current flowing along the length of the pin 130, within the sleeve 133 and electrically insulated from the sleeve, as was the case in the earlier implementation 100, the head 631 of this pin 630 provides the entirety of the current path within the sliding pin 630 in the series configuration, with current flowing from the head 631 of the pin 630 to a busbar 645 mounted to the head 631 of the pin 630. The conductive “sleeve” 633 used in the parallel current flow path of this implementation 600 therefore does not surround the series current flow path, but rather is offset from it along the length of the pin 630. Although the conductive sleeve 633 is still provided as a conductive layer on an insulating layer 632 in this implementation, with the insulating layer 632 providing a core of the pin and joining the head 630 to the sleeve 633, it will be appreciated that the sleeve 633 could be replaced with e.g. a conductive cylinder making up the full pin width - the movable conductor forming the current flow path in the parallel configuration is not necessarily in the form of a sleeve, as it does not necessarily surround a different current flow path. Indeed, the pin 630 could be symmetrical with two “heads” 631, 633, each providing a current path in one of the two positions. As for the sliding pin implementations described earlier, the pins 630 have an at least substantially constant width at least along the portion of the pin length between a right-most edge of the right-most contact and the left-most edge of the left-most contact to facilitate smooth, sliding, contact.

[0195] In the series configuration, as shown in Figure 26 (which is a sectional view along the centre line of a pin 630, offset from the view of Figure 25), the pin head 631 touches the fixed contact 624a at the lower end of the first conductor 622a (which is permanently connected to the first connector 602a). Current therefore flows from the first connector 602a, down the first conductor 622a, into the pin 630 via the first fixed contact 624a, through the head of the pin 630 leftwards (in the orientation shown) to the busbar 645, and along the busbar to the third connector 602c (via a corresponding pin 630 and conductor 622). The sleeve 633 is not used in this position. In the parallel configuration, as shown in Figure 27 (which is a sectional view along the centre line of a pin 630, as for Figure 26, but with the movable body 650 in the second position), the pin 630 has moved to the left (in the orientation shown), and the pin head 631 no longer contacts the first fixed contact 624a. No current therefore flows through the pin head 631 or busbar 645 in this position. Instead, the sleeve 633 touches both the first fixed contact 624a and the second fixed contact 624b, so providing a direct current path between the two fixed contacts 624a, b, and thereby between the corresponding connectors 602a, 602b.

[0196] In some implementations, canted coils springs provide the only physical contact between the fixed contacts 624a, 624b and the conductive pathways of the pins 630, so all current flows through the coil springs. As discussed above for the other pin design 130, especially in the series position, the current may be relatively high and the relatively small cross-sectional area of the coil spring may result in unwanted Joule heating (resistive heating) of the contact. The contacts may be shaped to increase the cross-sectional area of the flow path - for example, a “lip” or ridge on the pin 630 may be provided to make contact with the conductor 622a on which the coil spring is mounted, so increasing the overall cross-sectional area of the electrical contact and so reducing Joule heating. In such implementations, a corner of the conductor 622a nearest the lip on the pin may be slanted / angled, or otherwise shaped, so as to provide a larger contact surface for the lip on the pin. The lip may increase the pin’s circumference sufficiently that the pin cannot move further to the right than the position in which the lip on the pin touches the conductor 622a, and may therefore define a limiting position for the pin 630 in the first position. As shown in Figure 27, the pin 630 may have a head 631 that is too large to fit through the opening in the conductor 622a - an edge of this head nearest the conductor 622a may provide the ridge which increases the contact area. In some implementations with such a lip, the pin 630 may be biased towards the conductor 622a (actively or passively) so as to improve contact. In some implementations, a similar lip may be provided for the second (parallel) position - by the “head” of this current section where present, or by an introduced ridge - to increase the contact area between the parallel current pathway 633 of the pin 630 and the respective conductor 622b. In alternative or additional implementations, the busbar 645 between adjacent pins 630 may be arranged to provide an increased contact area, for example having a protrusion extending from the busbar 645 towards the conductor 622a and arranged to make contact with the conductor 622a in the first position. The conductor 622a of such implementations may be arranged to facilitate this additional contact, for example by being shaped to have a protrusion extending towards the busbar 645 (instead of being a simple vertical bar as in the examples pictured), or by the intervening insulting material shown in the examples pictured being removed such that the protrusion from the busbar 645 can reach the conductor 622a. The protrusion on the busbar 645 may be a raised straight-line ridge extending along the length of the busbar 645, and arranged to contact both conductors 622, so providing extra contact area for two fixed contacts. Alternatively, the busbar 645 may comprise two discrete protrusions, one for each pin 630 / conductor 622, or more discrete protrusions, optionally with multiple protrusions per pin 630 / conductor 622 (a single protrusion per pin may be preferred, however, as tolerancing considerations indicate that making and breaking of contact for multiple separate pairs of electrical contacts is unlikely to be perfectly simultaneous). Alternatively, the busbar 645 may comprise a ridge which encircles each pin, optionally with a connecting portion between the encircling ridges for each pin. Any suitable shaping of the contact may therefore be used to provide the increased contact area desired to reduce Joule heating - the increased contact area may be provided by either or both of the shaping of the fixed contact and the shaping of the movable contact - for example in implementations in which the intervening insulting material shown in the examples pictured is removed and the conductor 622a comprises a protrusion extending towards the busbar 645, no shaping of the busbar may be used.

[0197] Figure 25 provides a cross-sectional view of the whole switching assembly 600 including the actuator 652. The actuator 652 includes a voice coil motor in this example, although any suitable actuation arrangement - for example using a double-sided solenoid - may be used in other implementations. Figure 29 shows a rear view of the switching assembly 600 with a rear plate removed so as to expose connections to the voice coil motor used in the actuation arrangement 652 of this implementation.

[0198] Figure 32 shows a wheel assembly 1000 for an electric vehicle, showing the switching assembly 600 mounted on the stator 1110 of a motor 1100. The compact size of the assembly 600 may facilitate this mounting. In the implementation shown, the invertor connections 620, 622 are provided on an outward face of the switching assembly 600, facing away from the stator 1110, whereas the ends of the connectors 602 nearest to / facing the stator are used for connections to the motor coils. This arrangement may again facilitate a compact design, whilst allowing for the invertor connections 620, 622 to be made and broken easily, by removing plugs from sockets as and when required. The motor 1100 comprises the stator 1110 and a rotor 1120, and is mounted to a wheel 1200. The motor 1100 may be a hub motor, mounted on the hub of the wheel 1200. A tyre 1300 is also shown.

[0199] As described above, Figures 25 to 32 illustrate a different physical arrangement of the same electrical schematic shown in Figure 9. It will therefore be appreciated that a wide arrange of different physical implementations can be used without departing from the scope of the appended claims. By way of further example, in some implementations like that pictured in Figures 17 to 21, two busbars 333 could be provided - one on each side of the terminal block 301 between adjacent connectors 302 - and only one movable plate 330’ per group of four connectors 302 (rather than two) linking opposite connectors 302. It will therefore be appreciated that the physical implementations described above are provided by way of illustrative example only, and are not intended to be limiting.

[0200] In addition, various different electrical schematics may be developed and physically implemented based on the concepts disclosed herein. For example, Figure 33 illustrates electrical schematics for star (Figure 33A) and delta (Figure 33B) configurations of a star-delta switching assembly 700 very like the assembly 400 described above with respect to Figure 23, but in which the circuitry is arranged differently within the fixed body 401, 701. As a result of the different arrangement, the current flow path within the movable body 450 differs between the star and delta configurations, as well as the current flow path within the fixed body 701 differing between the star and delta configurations. This different arrangement allows one fixed contact 424b to be eliminated for the final phase (phase C), so potentially reducing assembly size and / or weight, as well as complexity. This changeability for current flow path both within the fixed body 701 and within the movable body 450 may therefore allow for more compact switching assembly designs.

[0201] Whereas in the implementation shown in Figure 23 each phase A, B, C has a row of three associated fixed contacts, arranged parallel to and immediately adjacent to a pin 430 for that phase, in the implementation of Figure 33, the final phase C has only two fixed contacts. The second end of the final coil of the final phase (Cl, in the example pictured) is connected to a permanent joining point within the fixed body 701 instead of re-joining the rest of the circuit via fixed contact 424a touching the pin 430. A single fixed contact 724b’ therefore takes the place of the two fixed contacts 424a and 424b in this implementation. Whilst the movable body 450 may be identical to that used for the embodiment shown in Figure 23, the current flow through the movable body 450 is different between the star and delta configurations in this implementation 700, because the pin 430 for the final phase, C, is not used in the star configuration (this pin is only used in the delta configuration). It will be appreciated that this configuration 700 could be used as part of a series-parallel-delts-star switching assembly, too.

[0202] In addition, whilst the above description focuses on moving a movable body 150, 250, 350, 450, 550 between two positions - a first position and a second position - the same movable body may be movable between three or more positions. For example, the switching assembly 100, 200, 300, 400 may have a third position which is a “neutral” position where neither electrical configuration is selected No current may flow in this third position, and an associated motor may be off.

[0203] As such, it is apparent that a wide variety of switching assemblies may be developed without departing from the scope of the appended claims.

Claims

CLAIMS1. A mechanical electronic switching assembly for an electric motor, said motor being a multiphase motor comprising a winding for each phase, the windings being arranged such that each phase comprises a number of phase fractions, each phase fraction extending between a pair of terminals, the mechanical electronic switching assembly comprising: a fixed body comprising a plurality of fixed contacts each arranged to be permanently connected to a corresponding terminal of a corresponding phase fraction; at least one moveable body that can be moved with respect to the fixed body between: a first position, in which the phases are arranged in a first electrical configuration; and a second position, in which the phases are arranged in a second electrical configuration, wherein the second electrical configuration is different from the first electrical configuration, wherein the at least one movable body comprises a plurality of movable contacts each arranged to contact at least one of the fixed contacts of the fixed body in at least one of the first configuration and the second configuration, and wherein the at least one movable body and the fixed body together are arranged to provide two different current flow paths such that the electrical configuration of phase fraction terminals can be reconfigured between the first electrical configuration and the second electrical configuration by selecting the corresponding current flow path, and wherein each current flow path has a portion provided by the movable body and a portion provided by the fixed body, and wherein both portions of the current flow path vary between the first electrical configuration and the second electrical configuration; and an actuator arranged to move the at least one moveable body between the first position and the second position.

2. The mechanical electronic switching assembly of Claim 1, further comprising a biasing means arranged to bias the movable contacts and fixed contacts together, wherein a direction of action of the biasing means is not parallel to a direction of movement of the actuator, and wherein optionally the biasing means itself provides at least one of the contacts .

3. The mechanical electronic switching assembly of Claim 1 or Claim 2, wherein the at least one moveable body can be moved with respect to the fixed body so as to move the phases between more than two different electrical configurations, and wherein optionally the mechanical electronic switching assembly comprises two separably-moveable movable bodies each arranged to be moved with respect to the fixed body between a first position and a second position so as to move the phases between two different electrical configurations, so as to provide four different electrical configurations.

4. The mechanical electronic switching assembly of any preceding claim, wherein the at least one moveable body is arranged to be moved linearly with respect to the fixed body .

5. The mechanical electronic switching assembly of any preceding claim, wherein the at least one moveable body is arranged to move slidingly with respect to the fixed body, and wherein optionally a surface of the movable body comprising at least one movable contact is arranged to slide along a surface of the fixed body comprising at least two movable contacts .

6. The mechanical electronic switching assembly of any preceding claim, wherein at least a region of the assembly comprising the fixed contacts and the contacts of the movable body is flooded with dielectric oil.

7. The mechanical electronic switching assembly of any preceding claim, wherein at least one of the following applies:(i) at least one fixed contact is arranged to form part of the current flow path in only one of the first electrical configuration and the second electrical configuration ; and(ii) at least one movable contact is arranged to form part of the current flow path in only one of the first electrical configuration and the second electrical configuration .

8. The mechanical electronic switching assembly of any preceding claim, wherein the movable body comprises a contact surface, the contact surface being arranged to form a current path directly between two of the fixed contacts in at least one of the first configuration and the second configuration, the two fixed contacts optionally being coplanar and in plane adjacent and parallel to a plane of the contact surface.

9. The mechanical electronic switching assembly of any preceding claim, wherein the movable contacts are sliding contacts, each arranged to slidably contact at least one of the fixed contacts of the fixed body.

10. The mechanical electronic switching assembly of any preceding claim, wherein at least one of the movable contacts is arranged to touch a different fixed contact in each of the first position and the second position, and optionally wherein the at least one movable contact is arranged to touch two different fixed contacts in at least one of the first position and the second position11. The mechanical electronic switching assembly of any preceding claim, wherein the movable body comprises n pins per phase, where n is equal to the number of phase fractions of that phase, the pins providing the only movable contacts, and wherein optionally the pins are rigidlyconnected together such that they move as one when the moveable body is moved between the first and second positions.

12. The mechanical electronic switching assembly of Claim 11, wherein each pin of that movable body provides two separate conductive paths, and wherein only a first conductive path of the pin is used in the first configuration and only a second conductive path of the pin is used in the second configuration.

13. The mechanical electronic switching assembly of any preceding claim, comprising, for at least one phase, two fixed contacts per phase fraction, and two conductive paths within the movable body, wherein the movable contacts are sliding contacts, and wherein, for each phase fraction: in the first position, a first fixed contact is connected to a second fixed contact by a first conductive path within the movable body, the first conductive path using at least a first sliding contact, and the second conductive path within the movable body is unused; and in the second position, the first fixed contact is connected to a third fixed contact, instead of to the second fixed contact, by a second conductive path within the movable body, the second conductive path using at least a second sliding contact different from the first sliding contact, and the first conductive path within the movable body is unused.

14. The mechanical electronic switching assembly of Claim 13, wherein the first electrical configuration is a series configuration, and the second electrical configuration is a parallel configuration.

15. The mechanical electronic switching assembly of Claim 13 or Claim 14, wherein the movable body comprises a plurality of pins, the first sliding contact being provided by a head of the pin and the second sliding contact being provided by a sleeve of the pin, and the fixed contacts being biased towards the pin.

16. The mechanical electronic switching assembly of any of Claims 1 to 10, wherein the movable body comprises, for at least one phase, (2n- l) slidable busbars for that phase to provide the movable contacts, where n is equal to the number of phase fractions, each slidable busbar providing a contact surface arranged to connect two fixed contacts in one of the first configuration and the second configuration, and to be unused in the other of the first configuration and the second configuration, and wherein optionally each slidable busbar and corresponding pair of fixed contacts are biased together, the direction of the biasing being perpendicular to the direction of busbar sliding.

17. The mechanical electronic switching assembly of Claim 16, wherein the slidable busbars are parallel to each other, and wherein the sliding direction is the same for all slidable busbars.

18. The mechanical electronic switching assembly of any of Claims 1 to 8, wherein: the fixed body comprises two conductors for each phase fraction, each conductor being arranged to provide at least one of the fixed contacts; and the movable body comprises a first conductive movable part arranged to move linearly so as to make and break contact between a pair of the conductors, and a second conductive movable part arranged to move linearly so as to make and break contact between a different pair of the conductors, and wherein optionally the actuator comprises a rotating part with a cam, and wherein the rotating part and cam lie between the first movable part and the second movable part, such that the cam pushes the first movable part in a first direction over a first angular range of rotation, and pushes the second movable part in a second direction, optionally opposite to the first direction, over a second angular range of rotation.

19. A mechanical electronic switching assembly for an electric motor, said motor being a multi phase motor comprising a winding for each phase, the windings being arranged such that each phase comprises a number of phase fractions, each phase fraction extending between a pair of terminals, the mechanical electronic switching assembly comprising: a fixed body comprising a plurality of fixed contacts each arranged to be permanently connected to a corresponding terminal of a corresponding phase fraction; at least one moveable body that can be moved slidably with respect to the fixed body between: a first position, in which the phases are arranged in a first electrical configuration; and a second position, in which the phases are arranged in a second electrical configuration, wherein the second electrical configuration is different from the first electrical configuration; and an actuator arranged to move the at least one moveable body between the first position and the second position, wherein the at least one movable body and the fixed body together are arranged to provide two different current flow paths such that the electrical configuration of phase fraction terminals can be reconfigured between the first electrical configuration and the second electrical configuration by selecting the corresponding current flow path, and wherein:the at least one movable body comprises a plurality of sliding contacts each arranged to contact at least one of the fixed contacts of the fixed body in at least one of the first configuration and the second configuration; and at least one of the fixed contacts is arranged to be unused, but optionally still touching a sliding contact, in one of the first electrical configuration and the second electrical configuration.

20. A mechanical electronic switching assembly for an electric motor, said motor being a multiphase motor comprising a winding for each phase, the windings being arranged such that each phase comprises a number of phase fractions, each phase fraction extending between a pair of terminals, the mechanical electronic switching assembly comprising: a fixed body comprising a plurality of fixed contacts each arranged to be permanently connected to a corresponding terminal of a corresponding phase fraction; at least one moveable body that can be moved with respect to the fixed body between: a first position, in which the phases are arranged in a first electrical configuration; and a second position, in which the phases are arranged in a second electrical configuration, wherein the second electrical configuration is different from the first electrical configuration, wherein the at least one movable body comprises a plurality of movable contacts each arranged to contact at least one of the fixed contacts of the fixed body in at least one of the first configuration and the second configuration, and wherein the at least one movable body and the fixed body together are arranged to provide two different current flow paths such that the electrical configuration of phase fraction terminals can be reconfigured between the first electrical configuration and the second electrical configuration by selecting the corresponding current flow path; an actuator arranged to move the at least one moveable body between the first position and the second position; and biasing means arranged to bias the movable contacts and fixed contacts together, wherein a direction of action of the biasing means is not parallel to a direction of movement of the actuator.

21. The mechanical electronic switching assembly of Claim 19 or Claim 20, wherein the current flow path is different within both the fixed body and the movable body between the different electrical configurations.

22. The mechanical electronic switching assembly of any preceding claim wherein at least one of the following applies:(i) the actuator is powered only when moving the movable body; and(ii) no locking mechanism is provided to lock the movable body in the first or second position.

23. An electric motor comprising a rotor, a stator, and the mechanical electronic switching assembly of any preceding claim mounted on the stator.

24. A wheel assembly for an electric vehicle, the wheel assembly comprising a wheel and the electric motor of Claim 23, and wherein the rotor of the motor is mounted to the wheel, optionally rigidly.

25. An electric vehicle comprising a chassis, a wheel, and a motor as claimed in Claim 23, and wherein optionally the motor is:(i) mounted to the chassis; or (ii) mounted to the wheel.

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