SWITCHING DEVICE FOR AN ELECTRIC MOTOR AND ELECTRIC MOTOR

A switching device for an electric motor comprises a fixed body, at least one moveable body that can be moved with respect to the fixed body between at least one first and one second position, in which the phases (104, 105, 016) are respectively in a first and a second electrical configuration, and a moving unit configured to move said moveable body between the first and the second position. This moving unit can be selectively coupled to the rotor of the electric motor so as to rotate with it and comprises a selecting device operationally placed between the rotor and the moveable body of the switching device and configured to transform each revolution of the rotor into a movement of the moveable body between the first and the second position.

This invention relates to a switching device for an electric motor and an electric motor comprising said switching device.

This invention is, therefore, particularly (but not exclusively) applicable to the automotive sector and, more precisely, to the design and manufacture of electric or electric/endothermic hybrid propulsion vehicles.

In relation to this sector, there has long been the need to extend the efficiency range of the electric motor in order to allow its use even in the absence of a mechanical transmission, or, in any case, in the presence of a simplified mechanical transmission.

To date, some methods are known, which are suitable for traction applications and use a suitable subdivision of the stator winding in different sections that can be selectively combined with each other in order to vary the motor “configuration”, thus being able to adapt it to the working conditions and extend its working range.

One such solution, perhaps the first, was studied by Eckart Nipp in his 1999 PhD thesis, which described a reconfigurable electric machine capable of achieving good performance in various operating conditions.

This solution, only illustrated on paper, has found limited application on the market, mainly due to its implementation/construction difficulties.

Until today, in fact, E. Nipp's idea has been developed and implemented by equipping motors with complex wiring and relays, the main drawbacks of which include the size, cost, and losses they introduce to the system.

Examples of these solutions are published in the patents WO2018/087689, U.S. Pat. No. 8,415,910 and WO2013/155601, that illustrate electrical machines with variable configuration equipped with several switches (at least 3 per phase) thanks to which each phase can change configuration.

In order to overcome these drawbacks, an innovative solution has recently been developed in which the switching device is electromechanical, consisting of a fixed body and a movable body that can be reciprocally moved so as to vary the electrical configuration of the stator, i.e. the connection between phases and/or phase fractions.

Despite its high technical/functional quality, this solution mostly requires an external actuator to move the moveable body in relation to the fixed body at the time of the “change”.

Given the high speeds and inertia involved, this could lead to problems in sizing the actuator and difficulties in designing systems that are both reliable and compact.

The purpose of this invention is, therefore, to provide a switching device for an electric motor that is able to overcome the drawbacks of the prior art described above.

In particular, the purpose of this invention is to provide a switching device that can be easily integrated into the electric motor and requires actuators that are easy to source or design.

In addition, the purpose of this invention is to provide a switching device for an electric motor that is very quick to implement and has low construction costs.

Said purposes are achieved with a switching device that has the technical features listed in one or more of the appended claims from 1 to 8, as well as with an electric motor that has the features of one or more of the claims from 9 to 12.

The electric motor comprises at least a first and a second phase extending between corresponding terminals.

Each phase is preferably provided with at least one first phase fraction and at least one second phase fraction, each extending between two ends.

Each terminal preferably corresponds to one end of a first or second phase fraction.

The switching device preferably comprises a fixed body equipped with a plurality of connection portions that can be joined to the ends of the first and second phase fraction and/or the terminals of each phase.

At least one moveable body is also, preferably, provided, which can be moved in relation to the fixed body between at least one first position and a second position.

In the first position, the moveable body arranges the phases in a first electrical configuration.

In the second position, the moveable body arranges the phases in a second electrical configuration.

It should be noted that the second electrical configuration is preferably separate from the first due to the connection between the first and second phase fraction within each phase and/or due to the reciprocal connection between the phases.

In addition, a moving unit is preferably provided and configured to move said moveable body between the first and the second position.

According to one aspect of the invention, the moving unit comprises a first rotating element and a second rotating element.

The first rotating element can be rotatably connected (i.e. in captive use) to the rotor of the electric motor, in order to rotate integrally with it.

The second rotating element is connected to the moveable body of the switching device and can be coupled with the first rotating element.

Preferably, moreover, the moving unit comprises an actuator operationally placed between the first and second rotating element.

The actuator is preferably configured to move the first and the second rotating element towards and apart from each other between a working position, in which the first and the second rotating element are rotatably connected, and a resting position, in which the first and the second rotating element are disconnected from each other.

The switching device preferably comprises a selecting device operationally placed between the second rotating element and the moveable body.

The selecting device is preferably configured to transform each revolution of the second rotating element into a movement of the moveable body between the first and second position.

Advantageously, in this way it is possible to exploit the rotor inertia to generate the movement of the moveable body between the first and the second position, requiring only a small actuator able to move the two rotating bodies away from and towards each other.

The selecting device preferably comprises at least one track made on said second rotating element and having at least one first portion and at least one second portion connected to each other by means of an exchange section.

There is at least one selection member linked to said track and moveable between at least one first operating position, in which it is linked to the first portion of the track, and a second operating position, in which it is linked to the second portion of the track.

A transmission unit is preferably placed between the selection member and the moveable body.

The transmission unit is preferably configured to position the moveable body in the first position when the selection member is in the first operating position and in the second position when the selection member is in the second operating position.

Advantageously, this system makes it possible to use rotor rotation as a power source for moving the moveable body at the critical actuation speeds required by the application, requiring an external actuator only for coupling/uncoupling operations, which are simpler and less stringent in terms of performance requirements.

The first portion of the track preferably comprises a first arc-shaped (of a circle) channel or profile of a smaller radius.

The second portion of the track comprises a second arc-shaped (of a circle) channel or profile of a greater radius.

Said arc-shaped channels therefore extend between two ends following the profile of a circumference, i.e. an arc of a circle.

Both channels or profiles preferably extend around a central axis of the second rotating element (i.e. the rotor rotation axis).

The exchange section connects said arc-shaped channels or profiles.

This exchange section preferably comprises, in addition, at least one moveable element between a first position, in which it allows the passage of the selection member from the first to the second portion, and a second position, in which it allows the passage of the selection member from the second to the first portion of the track.

More preferably, the exchange section comprises a first movable element linked to the first portion and a second movable element linked to the second portion.

The first element is moveable between a first position, in which it obstructs one exit end of the first portion, and a second position, in which it obstructs one entry end of the first portion of track.

The second element is movable between a first position, in which it obstructs one exit end of the second portion, and a second position, in which it obstructs one entry end of the second portion of track.

The exchange section preferably comprises a cross defined by a first and a second branch intersecting each other and each connected to one end of the first portion and one end of the second portion of track.

Each moveable element is configured to prevent the selection member from passing directly from the first to the second branch and vice versa.

Preferably, moreover, the selection member comprises an arm extending between a first end, slidably linked to said track, and a second, hinged end, and a fixed element (e.g. the casing of the electric motor).

The transmission unit preferably comprises a toothed coupling between said second end of the arm and said movable body shaped to transform a rotary mode of the arm into a corresponding (preferably counter-rotating) motion of the moveable body.

Advantageously, this system enables a quick and precise switching between the electrical configurations of the stator, being efficient and at the same time easily integrated into the machine.

With reference to the appended figures, the reference number1indicates a switching device for an electric motor100according to this invention.

The switching device1is therefore connected, or can be connected, to an electric motor100, preferably but not exclusively of the internal magnet type.

In particular, the electric motor100comprises a stator body, or stator101, and a rotor body, or rotor102, which is rotatably joined to the stator101to rotate about its own rotation axis “A”.

The stator body101is preferably housed inside a containment body “C” or casing.

The rotor102is preferably inserted into the stator101coaxially to it, at least to the stator cavity, and comprises a plurality of magnets, electromagnets, or windings designed to generate a magnetic field.

The stator101, in turn, is provided with a prismatic casing101aextending along said rotation axis “A” between two end faces103a,103b.

This casing101acontains a plurality of phases104,105,106angularly spaced apart and defined by corresponding windings.

The phases can be of various types, but are preferably defined by bar conductors suitably arranged in corresponding slots formed in the casing and electrically connected to each other at at least one free end (i.e. at an end face103aof the casing101a).

The electric motor100is, therefore, of the multiphase type, i.e. comprising a number of phases ranging from two and increasing depending on the type or application.

In the preferred embodiment, however, the electric motor100is at least a three-phase motor.

In other words, in the embodiment illustrated (for illustrative purposes only), the stator101comprises at least a first104, a second105, and a third phase106.

Each phase104,105,106extends between corresponding first104a,105a,106aand second terminals104b,105b,106b.

In the embodiment illustrated, the electric motor100preferably has fractionated phases.

Preferably, therefore, each phase104,105,106is provided with at least one first phase fraction107and at least a second phase fraction108, both extending between a first end107a,108aand a second end107b,108b.

It should be noted that, in this respect, one end107aof the first phase fraction107and one end108bof the second phase fraction108correspond to the terminals104a,104b,105a,105b,106a,106bof the phases104,105,106.

More precisely, the first end107aof the first phase fraction107and the second end108bof the second phase fraction108correspond, respectively, to the first104a,105a,106aand the second terminal104b,105b,106bof the corresponding first104, second105, or third phase106.

In other words, each terminal104a,104b,105a,105b,106a,106bcorresponds to an end107a,108bof a first107or second phase fraction108.

The phase fractions107,108of each phase104,105,106are like said coils or, preferably, bars (or sets of bars/hairpins) connected to each other.

The phases104,105,106and/or the phase fractions107,108of each phase can be connected together in a suitable way in order to change the operating configuration of the electric motor100.

Due to this, a switching device1configured to change the connection between the phases104,105,106and/or phase fractions107,108, in order to change the electrical configuration of the motor100, is provided.

In particular, the switching device1is configured to actuate the change in configuration when a pre-fixed switching speed (or any other relevant parameter) is reached.

The switching device1comprises a fixed body2equipped with a plurality of connection portions3that can be joined to the ends107a,108a,107b,108bof the first107and second phase fraction108and/or to the terminals104a,104b,105a,105b,106a,106bof each phase104,105,106.

The fixed body2is preferably made of aluminium.

In a preferred embodiment, the fixed body2is made in the form of a busbar in order to define the electrical connection between the conductor bundles of the winding of the electric motor100.

The connection portions3are defined by seats where the free ends of the phases104,105,106or phase fractions107,108, which, as mentioned above, are preferably in the form of a bar (hairpin), are engaged.

It should be noted that, preferably, the connection portions3of the fixed body2correspond, in number, to the number of terminals or ends of the phase fractions107,108, depending on the embodiment.

In other words, in fractionated phase embodiments, the number of connection portions3of the fixed body2is preferably equal to twice the number of phases multiplied by the number of “fractions” (i.e. phase fractions) of each phase. In the illustrated embodiment, for example, the number of connection portions3is 12.

In non-fractionated phase embodiments, on the contrary, the number of connection portions3of the fixed body2could be limited to the number of phase terminals (i.e. twice the number of phases).

In addition, the fixed body2preferably comprises at least one connecting jumper4connected to each first104a,105a,106aor second terminal104b,105b,106band extending from the corresponding terminal104a,104b,105a,105b,106a,106bto one free end4a.

In other words, as will be better clarified below, a connecting jumper4is joined to each terminal104a,104b,105a,105b,106a,106bof a phase104,105,106, each jumper defining an additional contact zone with said terminal104a,104b,105a,105b,106a,106bat its free end4a.

The switching device1comprises at least one moveable body5,10that can be moved in relation to the fixed body2.

The moveable body5,10can preferably be selectively moved in relation to the fixed body2between at least one first and one second position.

In the first position, the moveable body5,10arranges the phases104,105,106in a first electrical configuration.

In the second position, the moveable body5,10preferably arranges the phases in a second electrical configuration.

The second electrical configuration is separate from the first one due to the connection between the first107and the second phase fraction108within each phase104,105,106and/or due to the reciprocal connection between the phases104,105,106.

In other words, the movement of the moveable body5,10in relation to the fixed body2ensures that the electrical configuration of the electric motor1is modified by at least one first to at least one second configuration.

Structurally, in this respect, the moveable body5,10preferably has a plurality of contact portions6,11each joined to a corresponding end107a,108a,107b,108bor a corresponding terminal104a,104b,105a,105b,106a,106bof the phase104,105,106.

Each contact portion6,11comprises at least one first and one second connecting point separate and positioned so that the first point contacts the corresponding end or terminal in the first position and the second point contacts the corresponding end or terminal in the second position of the moveable body5,10.

According to this invention, the switching device1comprises a moving unit9configured to move said moveable body5,10between the first and the second position.

The moving unit9can be selectively coupled with the rotor102in order to rotate with it and use its inertia to move the moveable body between the first and second position.

More precisely, the moving unit9comprises a selecting device20operationally placed between the rotor102and the moveable body5,10of the switching device1.

The selecting device20is configured to transform each rotor revolution102into a movement of the moveable body5,10between the first and second position.

Advantageously, in this way, the synchronisation of the rotor and the moving unit, which rotating with the rotor enables maximum actuation speed and thus overcomes the drawbacks found in the prior art, is ensured.

The moving unit9preferably comprises a first rotating element21rotatably connected (or attached) to the rotor102to rotate integrally with it.

The first rotating element21is preferably fitted to a shaft102athat is coaxial to the rotor102and is bound to rotate with it.

The moving unit9comprises, in addition, a second rotating element22connected to said moveable body5,10and that can be selectively coupled with the first rotating element21.

In this respect, an actuator23operationally placed between the first21and second rotating element22is preferably provided.

The actuator23is configured to move these first21and second rotating elements22close to and away from each other between a working position and a resting position.

In the working position, the first21and the second rotating element22are rotatably connected to each other, so that the first rotating element21transmits the rotation of the rotor102(i.e. of the shaft102a) to the second rotating element22.

In the resting position, the first21and the second rotating element22are attached to each other. Therefore, the first rotating element is free to rotate integrally with the rotor102while the second rotating element is idle or blocked in a specific position.

The first rotating element21preferably comprises a clutch disk21afitted to the shaft102aand slidably linked to it to move between said working and resting positions.

In other words, the first rotating element21(in particular, the clutch disk21a) is rotatably connected and, at the same time, slidably linked to the shaft102a.

The actuator23is preferably of the linear type and is configured to translate the first rotating element along the shaft102abetween a position removed from the second rotating element22, corresponding to the resting position, and a position close to, in particular in contact with, the second rotating element22.

In the preferred embodiment, the actuator23is defined by a hydraulic or pneumatic piston. Alternatively, in any case, this actuator could also be of another kind, for example electric.

The selecting device20is connected to the second rotating element22and is placed (structurally and/or operationally) between said second rotating element22and the moveable body5,10of the switching device1.

As mentioned above, the task of the selecting device20is to transform each revolution of the second rotating element22(and thus of the rotor102) into a movement of the moveable body5,10between the first and second position.

The selecting device20makes it possible to “select” (hence the name) the position of the moveable body5,10and, thus, the electrical configuration of the motor100, depending on the rotor rotation.

The selecting device20preferably comprises at least one track24, a selection member25, and a transmission unit26.

The track24is made on said second rotating element22and has at least one first portion24aand at least one second portion24bconnected to each other by means of an exchange section24c.

The selection member25is, thus, linked to said track24and is moveable between at least one first operating position, in which it is linked to the first portion of the track24a, and a second operating position, in which it is linked to the second portion of the track24b.

The transmission unit26is placed between the selection member25and the moveable body5,10and is configured to position the moveable body5,10in the first and in the second position respectively when the selection member25is in the first operating position and in the second operating position.

It should be noted that the track24preferably defines a cam profile and the selection member25comprises a cam follower25aslidably linked to the cam (i.e. to the track).

Therefore, a movement of the track24, along which the selection member25runs, in particular the cam follower25a, corresponds to a rotation of the second rotating element22.

In particular, the selection member25comprises an arm27extending between one first end27aand one second end27b.

The first end27ais slidably linked to the track24; therefore, in the preferred embodiment, the first end27aof the arm27defines the cam follower25a.

The second end27bis hinged to a fixed element (in relation to the moveable body5,10and to the moving unit9).

This second end27bis preferably hinged to the fixed body2of the switching device, to the stator101, or to the casing X of the electric motor100.

The transmission unit26comprises, thus, a toothed coupling28between the second end27bof the arm27and the moveable body5,10.

This toothed coupling28is shaped to transform a rotary motion of the arm27around its own pin axis “C” into a corresponding movement of the moveable body5,10.

The movement of the moveable body5,10can be rotary or translatory, preferably counter-rotatory in relation to the arm27.

In the preferred embodiment, the toothed coupling28comprises a toothed wheel28aattached to the arm27and a toothed profile28b(linear or curved) that is integral with the moveable body5,10.

The arm27is, therefore, configured to oscillate around its own pin axis between a plurality of angular positions determined by the track24, determining the movement of the moveable body5,10between the first and the second position as a function of this oscillation.

In more detail, the track24is preferably defined by a plurality of arc-shaped channels or profiles, preferably an arc of a circle. As mentioned above, the arc-shaped channels or profiles preferably follow an arc of a circle between two respective ends and each have a constant radius with respect to the central axis “B”.

The first portion24aof the track24preferably comprises at least one first arc-shaped channel29aor profile with a smaller radius.

The second portion24bof the track24comprises at least one second arc-shaped channel29bor profile with a smaller radius.

Both the arc-shaped (of a circle) channels or profiles extend around a central axis “B” of the second rotating element22, i.e. of the rotor102.

Each first arc-shaped channel29ais connected to a corresponding second arc-shaped channel29bby means of a corresponding exchange section24c.

The exchange section24cpreferably comprises at least one moveable element30a,30bbetween a first position, wherein it allows the passage of the selection member25from the first24ato the second portion24b, and a second position, wherein it allows the passage of the selection member25from the second24bto the first portion24a.

More precisely, the exchange section24ccomprises a first moveable element30alinked to the first portion24aand a second moveable element30blinked to the second portion24b.

The first moveable element30ais moveable between a first position, in which it obstructs one exit end of the first portion24a, and a second position, in which it obstructs one entry end of the first portion24aof track24.

Similarly, the second moveable element30bis movable between a first position, wherein it obstructs one exit end of the second portion24b, and a second position, wherein it obstructs one entry end of the second portion24bof track24.

It should be noted that, preferably, the first moveable element30ain the second position faces the second moveable element30bin the first position, thus defining a first passage channel for the selection member25from the exit end of the first portion24ato the entry end of the second portion24b.

In addition, the first moveable element30ain the second position faces the second moveable element30bin the first portion, thus defining a second passage channel for the selection member25from the exit end of the second portion24bto the entry end of the first portion24a.

Advantageously, in this way, the correct reciprocal moving between the track24and the selection member25is ensured, avoiding system malfunctions.

More specifically, the exchange section24cpreferably comprises a cross31defined by a first and a second branch intersecting each other and each connected to one end (entry or exit) of the first24aand of the second portion24bof track24.

In particular, the first branch preferably extends between the exit end of the first portion24aand the entry end of the second portion24bof track24.

The second branch extends between the exit end of the second portion24band the entry end of the first portion24aof track24.

It should be noted that, in this respect, each moveable element30a,30bis configured to prevent the selection member25from passing directly from the first to the second branch and vice versa. Advantageously, this maximises the system's reliability.

Each moveable element30a30bpreferably comprises a springback member (not illustrated) designed to enable the movement of the same between the first and the second position following a pre-fixed thrust action and configured to return the moveable element30a,30bfrom the second to the first position at the completion of this action.

Therefore, the first position of the moveable element30a,30bis preferably a considerably stable position, while its second position is a considerably unstable position.

Advantageously, in this way, the moveable element30a,30bis autonomously driven by the selection member25(in particular by the cam follower25a) in its movement along the track, avoiding the necessity of using active actuators or selectors that necessitate control.

The switching device comprises, in addition, a control unit14joined to the moving unit9in order to drive it, according to the operating conditions of the electric motor100.

This control unit14is preferably joined to the vehicle's control unit or sensor means capable of transmitting information related to the operating parameters of the vehicle and/or the electric motor100itself.

In the embodiment described here, the control unit14is linked to the actuator23and is configured to drive it in accordance with the operating conditions of the electric motor100.

In particular, the control unit14is configured to drive the actuator23so as to move the first rotating element21from the resting position to the working position when the rotor reaches the switching speed.

Specifically, on receiving a signal indicating that the switching speed has been reached, the control unit14is programmed to send a signal representing a movement from the resting position to the working position to the actuator23.

In addition, the control unit14is configured to keep the first rotating element21in the working position for a number of rotor revolutions102corresponding to the displacement of the moveable body5,10from the first to the second position.

Finally, the control unit14is configured to guide the actuator23so as to move the first rotating element21from the working position to the resting position when said number of revolutions is reached.

In other words, on receiving a signal representing the attainment of said number of revolutions (or, in any case, identifying the configuration change), the control unit14is programmed to send a signal representing a movement from the working position to the resting position to the actuator23, thus detaching the first21from the second moveable body22and stopping the movement of the selection member25in the track24.

Advantageously, the solution described until this point significantly facilitates the execution of the switching, limiting the electronics necessary to driving a simple, linear actuator23—simple to source/design and, above all, to integrate into the system.

It should be noted that, in the preferred embodiment, the shaft102ato which the first rotating element21is coupled exits (i.e. protrudes from) the rear of the rotor102. In other words, the shaft102aextends in the opposite direction to the end for connecting the charge to the motor, considered to be the front end in this text.

Therefore, according to a preferred embodiment of the invention, the casing101aof the stator101extends between two end faces103a,103bwherein a power shaft102bof the motor100protrudes from a first face103a(front), the shaft being coupled to a charge, and said shaft102a, or auxiliary shaft, protrudes from a second end face103b(rear).

Advantageously, this makes it possible to position the switching device1and the moving unit9in a zone of the electric motor100that does not involve the elements for mechanically transmitting motion, rationalising the dimensions and facilitating both the installation and the maintenance.

In accordance with a preferred embodiment of the invention, the moveable body5,10of the switching device can be moved in relation to the fixed body2, including into a third position.

In the third position (separate from the first and second) an electrical circuit defined by said phases104,105,106is in an open condition.

In other words, the third position is a neutral position wherein the stator phases are in a non-conductive state.

Advantageously, this makes it possible to run the motor in idle, for example, keeping the rotor firmly bound to the vehicle's wheel assembly without the need to introduce a clutch or disconnect clutch to operate when the electric motor is not operating.

The moveable body5,10can preferably be moved along a stroke that goes from the first to the second position, in which said third position is intermediate between said first and said second position.

In accordance with this embodiment, the moving unit9also has some additional features.

In particular, the moving unit9is preferably configured to transform each revolution of the second rotating element into a movement of the moveable body5,10between the first, the second position, and the third.

In this respect, the second rotating element22preferably has a track24that is also equipped with a third portion24d, connected to the first24aand/or to the second portion24bby means of one or more exchange sections24c(refer to the previous paragraphs for a detailed description of such).

The selection member25can, thus, be moved in at least one third operating position, additional to the first two, and the transmission unit26is configured to position the moveable body5,10into the third position when the selection member is in the third operating position.

In the preferred embodiment, the third track24dis placed between the first24aand the second24b; there are, therefore, two exchange sections24c, one between the first24aand the third portion24d, and one between the third24dand the second portion24b.

More precisely, the third portion24dof the track24comprises at least one third arc-shaped channel29cor profile, with a medium radius between the first29aand the second channel29b.

More specifically, in this embodiment, the track24comprises:

a first channel29a, with a smaller radius, extending around the central axis “B” between an entry end and an exit end;

a first exchange section provided with a first and a second branch that intersect, branching out respectively from the entry end and the exit end;

a third channel29b, with a medium radius, extending in a position radially external to the first channel29abetween an entry end, connected to the second branch of the first exchange section, and an exit end;

a third channel29b, with a medium radius, extending in a position radially external to the first channel29abetween an entry end and an exit end, connected to the first branch of the first exchange section;

a second exchange section provided with a first and a second branch that intersect and branching out, respectively, from the entry end of a third channel29dand from the exit end of the other third channel29d;

a second channel29b, with a larger radius, extending around the third channels29dbetween an entry end and an exit end connected, respectively, to the second and to the first branch of the second exchange section29d.

It should be noted that, in a preferred embodiment, the switching device1comprises a first5and a second moveable body10, which are moveable independently and reciprocally in relation to each other.

In other words, both the first5and the second moveable body10can be moved into respective first and second positions independently of each other.

In this way, the switching device1enables a plurality of operating configurations to be defined; this plurality is equal to the product of the number of positions that can be assumed by the first5and the second moveable body10.

With reference to the preferred embodiment, the switching device1makes it possible to obtain one or more of the following operating configurations:

a delta-series configuration, in which the first moveable body5is in the first position and the second moveable body10is in the second position;

a delta-parallel configuration, in which both the first moveable body5and the second moveable body10are in the second position;

a star-series configuration, in which the first moveable body5is in the second position and the second moveable body10is in the first position;

a star-parallel configuration, in which both the first moveable body5and the second moveable body10are in the first position.

In this embodiment, therefore, the switching device1could comprise two moving units9, both linked to the rotor102and able to be moved independently in their respective operating positions.

The invention achieves its intended purposes and significant advantages are thus obtained.

In fact, the presence of a switching device able to vary the electrical configuration of the motor without needing to provide an actuator capable of synchronising with the rotation of the rotor significantly simplifies the design and driving of the electric motor.

In addition, by exploiting the intrinsic synchronisation of the rotor with an element rotatably connected to it, the actuation speed of the moving unit is maximised, as is the system efficiency.