ELECTRIC MOTOR WITH TOROIDAL WIND AND COMMON MODE CURRENT FILTERING.

Abstract

The invention relates to an electric motor or alternator comprising a rotor having p≥1 pair(s) of magnetic poles, a stator (100) configured to cooperate at an air gap with said rotor to produce a mechanical force and / or an induced electrical voltage, said stator comprising a plurality N of coils (10⁴, 10⁴φ₁, 10⁴φ₂, 10⁴φ₃), characterized in that: - The coils are wound toroidally around the magnetic circuit of the stator, - The coils are wound and energized such that the orthoradial magnetic fluxes of the common-mode currents of each coil add together, so as to obtain a high inductance, to reduce said common-mode currents, - The plurality N of coils satisfies the following equation: N = M x Q x pxk, with: - M: number of phases, - k = 1, - Q = number of coils per pole pair and per phase. Figure [3]

Description

Title of the invention: TOROIDAL WIND AND FILTERING ELECTRIC MOTOR COMMON MODE CURRENTS. technical field

[0001] The present invention relates to an electric motor or alternator with toroidal winding, enabling the filtering of common mode currents.

[0002] The invention applies in particular to electric motors equipped with a frequency or speed variator. State of the art

[0003] As shown in [Fig. 1] from the prior art, electric motors are generally controlled by variable speed or frequency drives that control the motor speed by varying the frequency of the power supply using pulse-width modulation. The operation of these drives is based on the switching of high-frequency power transistors. This modulation is achieved by switching transistors on and off continuously, for example, insulated-gate bipolar transistors (IGBTs) or thyristors.

[0004] To control alternating current electric motors at variable speed, it is necessary to use an assembly consisting of a rectifier and an inverter if a sinusoidal voltage network with a fixed frequency is available, or an assembly consisting simply of an inverter if a DC voltage network is available.

[0005] Ideally, it is desirable that the sinusoidal voltages delivered by the inverter to the motor be perfect. Thus, since the voltages on the three phases are phase-shifted by 120°, the sum of the three voltages sent to the motor should be zero.

[0006] However, this is not the case since sinusoidal voltages are reconstructed by successive stages of DC voltages. These DC voltage stages are judiciously configured so that the recreated voltage waveform is overall sinusoidal. This is called pulse-width modulation (PWM). When the three phase voltages are summed, an identical alternating voltage remains, in phase across all three phases, called the common-mode voltage. In other words, it is the residual voltage after the summation of the three voltages applied to the three phases.

[0007] These common-mode voltages at the output of the drives give rise to high-frequency currents, known as common-mode currents, which flow from the inverter to the motor winding via the cable connecting the motor phases to the drive, and then return via the motor housing and bearings, through capacitors Interference can be diverted to the inverter's ground, for example, through the shielding of the cable connecting the motor to the drive. For a given common-mode voltage, the current depends on the impedance seen by the common-mode circuit.

[0008] However, these common mode currents have the disadvantage of damaging the bearing mechanisms on which rotating parts such as rotors are mounted.

[0009] It is known to use common-mode current filters, as shown in [Fig. 2], which comprise a magnetic circuit and windings such that the magnetic effects caused by differential-mode currents cancel each other out, while the magnetic effects caused by common-mode currents add together. Since the magnetic fluxes of the common-mode currents from each coil add together, a high inductance opposes the common-mode currents, which tends to reduce them. In summary, a common-mode current filter must have a minimum impedance for differential-mode currents and a maximum impedance for common-mode currents.

[0010] However, these common-mode current filters are relatively intrusive in installations including electric motors. Indeed, depending on the power, adding a filter can have adverse consequences in terms of mass, volume, efficiency, and ease of cooling.

[0011] One object of the present invention is to remedy at least one of the drawbacks of the prior art, previously described. Description of the invention

[0012] To this end, the invention relates to an electric motor or alternator comprising p>l pair(s) of magnetic poles, a stator configured to cooperate at an air gap with said rotor to produce a mechanical force and / or an induced electrical voltage, said stator comprising a plurality N of coils, characterized in that: - The coils are wound in a toroidal pattern around the stator's magnetic circuit, - The coils are wound and energized in such a way that the orthoradial magnetic fluxes of the common-mode currents of each coil add together, so as to obtain a high inductance, tending to reduce said common-mode currents, - The plurality N of coils satisfies the following equation: N = MxQxpxk, with: - M: number of phases, k = 1 - Q = number of coils per pole pair and per phase.

[0013] Thus, contrary to the prior art of toroidal architectures, according to which the plurality N of coils satisfies the equation N = MxQxpxk, with M: number of phases, Q = number of coils per pair of poles and per phase, k = 2, p: number of pairs of poles, the motor according to the invention uses a number of coils divided by two.

[0014] Indeed, in the prior art, k = 2 in order to optimize the distribution coefficient of the motor winding, which has the effect of increasing the torque-to-Joule-loss ratio of the motor.

[0015] According to the invention, the distribution coefficient of the motor winding is not optimized, but the toroidal winding of the motor with k = 1 allows for the filtering of common-mode currents. Indeed, the orthoradial fluxes due to the differential-mode currents of all phases cancel each other out in the stator magnetic circuit, while the orthoradial fluxes due to the common-mode currents of all phases add together in the stator magnetic circuit. The inductance of the common-mode circuit is thus higher, and the common-mode currents are therefore reduced. Thus, the filtering effect has virtually no effect on the differential-mode currents, while it opposes inductance to the common-mode currents.

[0016] Optional features of the invention, complementary or alternative, are stated below.

[0017] According to one embodiment, the electric motor or alternator has a cylindrical architecture with a radial field.

[0018] According to a particular configuration, the electric motor or alternator admits a cylindrical architecture with a radial field, two air gaps, and two rotors.

[0019] According to a preferred aspect of the cylindrical architecture radial field embodiment, the magnetic circuit of the stator consists of an assembly of sheets, such as for example a stack of sheets, made of Iron-Silicon, Iron-Nickel or Iron-Cobalt alloy.

[0020] Iron-Silicon alloys with a saturation induction of 2 T can be used, for example.

[0021] Iron-nickel alloys can also be used, which, on the other hand, are used in high-end applications and are used more in the manufacture of sensors and low-loss magnetic motors, due to their high permeabilities and low mass losses.

[0022] For applications with high volumetric and / or mass performance (defense, aeronautics and space markets), Iron-Cobalt alloys can be used preferentially due to their high level of saturation induction (Bsat > 2.3 T).

[0023] The use of sheet metal reduces losses induced by eddy currents. The surfaces of the sheet metal are insulated so that, when the sheets are stacked, electrical contact between them is limited. As a result, the eddy currents are confined within their respective sheets, unable to flow perpendicularly to the plane of the sheets. Consequently, the currents travel greater distances, which increases the electrical resistance and therefore reduces eddy current losses.

[0024] This phenomenon of reducing losses by eddy currents by lamination of the sheets works at low and high frequency.

[0025] Preferably, the thickness of said Iron-Silicon, Iron-Nickel or Iron-Cobalt alloy sheets is reduced, i.e. less than or equal to 0.2 mm, preferably less than or equal to 0.15 mm, even more preferably less than or equal to 0.1 mm.

[0026] The use of thin sheets not only reduces eddy current losses, but also limits the skin effect at high frequencies.

[0027] Indeed, at high frequencies, the eddy currents confined within each sheet tend to flow along the edges of the sheet. As the frequency increases, the currents become more confined to the edges, so that at high frequencies, the center of the sheet is no longer used.

[0028] Consequently, the flux distribution in the sheet metal is no longer homogeneous, and this can lead to saturation. Furthermore, the magnetic field created by the eddy currents can affect the main flux of the motor, leading to an attenuation of the main flux.

[0029] According to an alternative aspect of the cylindrical architecture radial field embodiment, the magnetic circuit of the stator is obtained by sintering powders of soft magnetic materials (Soft Magnetic Composites), or by additive manufacturing.

[0030] According to yet another alternative aspect of the cylindrical architecture radial field embodiment, the magnetic circuit of the stator consists of an assembly of sheets, such as for example a stack of sheets, amorphous or nanocrystalline.

[0031] Similarly, to limit eddy current losses, or even the skin effect at very high frequencies, the thickness of amorphous or nanocrystalline sheets is advantageously reduced, i.e. between 10 and 30 microns.

[0032] According to another embodiment, the electric motor or alternator has a discoid architecture with axial field.

[0033] According to a first configuration, the electric motor or alternator admits a discoid architecture with a single-air gap axial field.

[0034] According to a second preferred alternative configuration, the electric motor or alternator admits a discoid architecture with axial field, two air gap, and two rotors.

[0035] This two-rotor air gap configuration offers superior performance due to the presence of two rotors.

[0036] According to a preferred aspect of the axial field discoid architecture embodiment, the magnetic circuit of the stator consists of a winding of sheets of Iron-Silicon, Iron-Nickel or Iron-Cobalt alloy.

[0037] For example, Iron-Silicon alloys with a saturation induction of 2 T can be used.

[0038] Iron-nickel alloys can also be used, which, on the other hand, are used in high-end applications and are used more in the manufacture of sensors and low-loss magnetic motors, due to their high permeabilities and low mass losses.

[0039] For applications with high volumetric and / or mass performance (defense, aeronautics and space markets), Iron-Cobalt alloys can be used preferentially due to their high level of saturation induction (Bsat > 2.3 T).

[0040] To limit eddy current losses, or even the skin effect at very high frequencies, the thickness of the sheets in Iron-Silicon, Iron-Nickel or Iron-Cobalt alloy is advantageously reduced, i.e. less than or equal to 0.2 mm, preferably less than or equal to 0.15 mm, even more preferably less than or equal to 0.1 mm.

[0041] According to another preferred aspect of the axial field discoid architecture embodiment, the magnetic circuit of the stator consists of a winding of amorphous or nanocrystalline sheets.

[0042] Similarly, to limit eddy current losses, or even the skin effect at very high frequencies, the thickness of amorphous or nanocrystalline sheets is advantageously reduced, i.e. between 10 and 30 microns.

[0043] According to an alternative aspect of the axial field discoid architecture embodiment, the stator magnetic circuit is obtained by sintering powders of soft magnetic materials (Soft Magnetic Composites) or by additive manufacturing.

[0044] According to a particular configuration of the cylindrical architecture embodiment with radial field, and of the discoid architecture embodiment with axial field, the magnetic circuit of the stator is notched.

[0045] The invention also relates to the use of a motor according to the invention and powered by an inverter, in which no common mode current filter is arranged upstream of said motor. Brief description of the FIGURES

[0046] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which: - Fig. 1 is a schematic representation of an electric motor powered by a frequency converter according to a prior art. - Fig. 2 is a schematic representation of an electric motor powered by a frequency converter with common mode current filtering according to a prior art. - Fig. 3 is a schematic representation of a three-phase electric motor with cylindrical architecture and radial field, according to an example of an embodiment of the invention. - Fig. 4 is a schematic representation of the magnetic circuit of a stator of a three-phase electric motor with cylindrical architecture and radial field, according to another embodiment of the invention. - Fig. 5 is a schematic representation of the wound stator of the motor in Fig. 4. - Fig. 6 is a schematic representation of a rotor configured to cooperate with the magnetic circuit of Fig. 4. - Fig. 7 is a schematic representation of an electric motor with a discoid architecture and axial field, in this case a two-rotor air gap motor, according to an example of an embodiment of the invention. - Fig. 8 is a schematic representation of the magnetic fluxes of differential and common mode currents in a toroidal winding, following a coil winding that allows the cancellation of orthoradial fluxes due to differential mode currents, and the accumulation of orthoradial fluxes due to common mode currents.

[0047] It is understood that the embodiments described below are by no means limiting. In particular, variants of the invention may be conceived comprising only a selection of the features described below, isolated from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art. This selection includes at least one preferably functional feature without structural details, or with only a portion of the structural details if this portion alone is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0048] In particular, all the variants and embodiments described are combinable with each other if there is no technical obstacle to this combination.

[0049] In the figures and in the rest of the description, elements common to several figures retain the same reference. Detailed description of the FIGURES

[0050] Fig. 3 is a schematic representation of a non-limiting example of an embodiment of a three-phase electric motor with cylindrical architecture and radial field.

[0051] The electric motor comprises a rotor 200 having a pair of magnetic poles 204 and a stator 100 configured to cooperate at an air gap with said rotor to produce a mechanical force and / or an electrical voltage. The stator 100 comprises a plurality 3 of coils 104 wound toroidally around the magnetic circuit 101.

[0052] It is understood that the plurality N of three coils in total satisfies the following equation:

[0053] N = M xQx Pxk, with:

[0054] M = 3 phases,

[0055] k = 1

[0056] Q = 1 coil per pair of poles and per phase,

[0057] p = 1 pair of poles.

[0058] It is also understood, as shown in [Fig. 8], that the coils 104^104 ç2, 104^3 are wound on the magnetic circuit 101 and supplied so that, when they are respectively supplied by the differential currents Idiff^Idiff^ Idiff(p3, the orthoradial magnetic fluxes Odiffjpi, <hdiff(p2, Cbdiff^ s’annulent.

[0059] It is also understood, as shown in [Fig. 8], that the coils 104, 104fp2, and 1043 are wound on the magnetic circuit 101 and energized such that the magnetic fluxes Orne of the common-mode currents Imc add up. This results in an increase in the inductance L, which is expressed as the sum of the magnetic fluxes Orne divided by the current Imc. This increased inductance, in turn, tends to reduce the common-mode currents.

[0060] FIGURES 4, 5 and 6 schematically represent another non-limiting example of a three-phase electric motor with cylindrical architecture and radial field.

[0061] More specifically, the electric motor comprises a rotor 200 shown in [Fig. 6], having a pair of magnetic poles 204, and a stator 100, shown in [Fig. 5], configured to cooperate at an air gap with said rotor to produce a mechanical force and / or an electrical voltage. The stator 100 comprises a plurality of 12 coils 104, 104, 104 toroidally wound around the magnetic circuit 101.

[0062] It is understood that the plurality N of twelve coils in total satisfies the following equation:

[0063] N = MxQxpxk, with:

[0064] M = 3 phases,

[0065] Q = 4 coils per pole pair and per phase,

[0066] p = 1 pair of poles,

[0067] k = 1

[0068] The coils 104 are further wound and energized so that the orthoradial magnetic fluxes of the common mode currents of each coil add together, so as to obtain a high inductance, which reduces the common mode currents.

[0069] The magnetic circuit 101 of the stator 100 shown in [Fig. 4] has the shape of a hollow tube formed to accommodate a rotor. The magnetic circuit 101 includes slots formed on its outer circumferential surface as well as on its inner circumferential surface. In particular, the magnetic circuit 101 has twelve slots distributed along the ortho-radial direction with an angular pitch of 30°.

[0070] These notches extend in the axial direction of the magnetic circuit 101 and define internal 102 and external 103 housings, so as to receive an electrical conductor disposed in said housing and wound toroidally around the magnetic circuit 101, to form a coil.

[0071] As shown in [Fig. 5], each housing receives a toroidal winding of electrical conductors. Each conductor may comprise one or more electrical wires, in particular made of copper or aluminum, covered with an insulator.

[0072] Advantageously, the conductors can be assembled into twisted strands.

[0073] The rotor 200, shown in [Fig.6], is in the form of a cylinder comprising a rotation axis and an outer surface.

[0074] The rotor 200 comprises two opposite pole magnets 204 mounted on a magnetic circuit 203, themselves mounted on a shaft 202, and held by a collar 201.

[0075] The magnetic circuit 203 can be made by machining a single piece, or by stacking pre-cut sheets and then assembling them.

[0076] In cylindrical architecture radial field electrical machine configurations, the magnetic circuit of the stators is often made up of an assembly of laminations, such as a stack of laminations.

[0077] The use of sheet metal reduces losses induced by eddy currents. The surfaces of the sheet metal are insulated so that, when the sheets are stacked, electrical contact between them is limited. As a result, the eddy currents are confined within their respective sheets, unable to flow perpendicularly to the plane of the sheets. Consequently, the currents travel greater distances, which has the effect of the effect of increasing electrical resistance and consequently reducing eddy current losses.

[0078] This phenomenon of reducing losses by eddy currents by lamination of the sheets works at low and high frequency.

[0079] Preferably, the thickness of said sheets of Iron-Silicon, Iron-Nickel or Iron-Cobalt alloy is reduced.

[0080] Thicknesses of less than or equal to 0.2 mm may be preferred, preferably less than or equal to 0.15 mm, even more preferably less than or equal to 0.1 mm.

[0081] The use of thin sheets not only reduces eddy current losses, but also limits the skin effect at high frequencies.

[0082] Indeed, at high frequencies, the eddy currents confined within each sheet tend to flow along the edges of the sheet. As the frequency increases, the currents become more confined to the edges, so that at high frequencies, the center of the sheet is no longer used.

[0083] Therefore, the distribution of the flux in the sheet metal is no longer homogeneous and this can lead to saturations.

[0084] According to an alternative aspect of the cylindrical architecture radial field embodiment, the magnetic circuit of the stator is obtained by sintering powders of soft magnetic materials (Soft Magnetic Composites), for example highly alloyed Fe6.5Si powders, phosphorus alloy powders, iron powders.

[0085] Soft magnetic materials are characterized by high permeability, low coercive force and low magnetic losses.

[0086] According to another alternative aspect of the cylindrical architecture radial field embodiment, the magnetic circuit of the stator can be obtained by additive manufacturing.

[0087] According to yet another alternative aspect of the cylindrical architecture radial field embodiment, the magnetic circuit of the stator can be made up of an assembly of sheets, such as for example a stack of sheets, amorphous or nanocrystalline.

[0088] These amorphous or nanocrystalline sheets can have very small thicknesses, i.e. between 10 and 30 microns, which makes it possible to limit eddy current losses, or even the skin effect at very high frequencies.

[0089] These amorphous or nanocrystalline sheets are produced by a process known as rapid liquid solidification, which results in very thin but very brittle sheets. The key characteristic of these sheets is that only wound, not stacked, magnetic circuits can be produced.

[0090] These sheets are obtained in the form of ribbons by rapid solidification of a liquid. The alloy is amorphous, meaning that the atoms constituting it do not exhibit long-range order.

[0091] For certain particular atomic compositions, it will be possible by controlled crystallization of the amorphous alloy to obtain biphasic materials comprising a nanocrystalline phase included in a matrix which remains amorphous.

[0092] Amorphous and nanocrystalline materials exhibit low magnetic anisotropy which can be adapted to the applications targeted by post-quenching heat treatments.

[0093] Their magnetic properties are remarkable: a low coercive field, high permeabilities (impedance or initial), low electromagnetic losses and an ease of controlling the properties by heat treatments.

[0094] Depending on their compositions, these alloys have saturation magnetizations between 0.5 and 1.7 T with magnetostriction values ​​that can be close to 0.2.10 x up to reach 35.10 6.

[0095] Fig. 7 is a schematic representation of a three-phase electric motor with a discoid architecture and axial field, according to an example of an embodiment of the invention.

[0096] More particularly, the electric motor admits a discoid architecture with axial field two-air gap with two rotors 200a, 200b.

[0097] The electric motor comprises two rotors 200a, 200b, each having a plurality of 8 pairs of magnetic poles 204a, 204b, and a stator 100 configured to cooperate at an air gap with said rotor to produce a mechanical force and / or an electrical voltage. The stator 100 comprises a plurality N = 24 coils 104 wound toroidally around the magnetic circuit 101.

[0098] It is understood that the plurality N = 24 of the coils satisfies the following equation:

[0099] N = MxQxpxk, with:

[0100] M = 3 phases,

[0101] k=l,

[0102] Q = 1 coil per pole and per phase,

[0103] p = 8 pairs of poles.

[0104] The coils 104 are further wound and energized so that the orthoradial magnetic fluxes of the common mode currents of each coil add together, so as to obtain a high inductance, which reduces the common mode currents.

[0105] The magnetic circuit 101 of the stator 100 shown in [Fig. 7] has the shape of a hollow tube. The coils are wound directly onto the magnetic circuit 101 of the stator in a toroidal manner. The stator 100 does not have any slots. The toroidal winding consists of electrical conductors. Each conductor may comprise one or more electrical wires, in particular made of copper or aluminum, covered with insulation.

[0106] Advantageously, the conductors can be assembled into twisted strands.

[0107] The rotors 200, shown in [Fig.7], each have the form of a disk comprising monobloc magnets 204a, 204b distributed radially on one of their faces.

[0108] The magnetic circuit of the rotor 200 can be made by machining a single piece, or by winding sheets.

[0109] According to another embodiment not shown, the electric motor could admit a discoid architecture with a single-air gap axial field.

[0110] According to another embodiment not shown, the electric motor could admit a discoid architecture in which the magnetic circuit of the stator has notches.

[0111] In configurations of electrical machines with a discoid architecture and axial field, the magnetic circuit of the stators can consist of a winding of laminations.

[0112] According to a first embodiment, the magnetic circuit of the stator with discoid architecture with axial field can be made of a winding of sheets of Iron-Silicon, Iron-Nickel or Iron-Cobalt alloy, or of amorphous or nanocrystalline sheets.

[0113] To limit eddy current losses, or even the skin effect at very high frequencies, the thickness of the sheets in Iron-Silicon, Iron-Nickel or Iron-Cobalt alloy is advantageously reduced, i.e. less than or equal to 0.2 mm, preferably less than or equal to 0.15 mm, even more preferably less than or equal to 0.1 mm.

[0114] According to a second embodiment, the magnetic circuit of the stator with a discoid architecture with axial field can be obtained by sintering powders of soft magnetic materials (Soft Magnetic Composites), for example highly alloyed Fe6.5Si powders, phosphorus alloyed powders, iron powders.

[0115] Soft magnetic materials are characterized by high permeability, low coercive force and low magnetic losses.

[0116] According to another alternative aspect of the axial field discoid architecture embodiment, the stator magnetic circuit can be obtained by additive manufacturing.

[0117] According to a third embodiment, the magnetic circuit of the stator with a discoid architecture with axial field can be made up of a winding of amorphous or nanocrystalline sheets.

[0118] These amorphous or nanocrystalline sheets can have very small thicknesses, i.e. between 10 and 30 microns, which makes it possible to limit eddy current losses, or even the skin effect at very high frequencies.

[0119] These amorphous or nanocrystalline sheets are produced by a process known as rapid liquid solidification, which results in very thin but very brittle sheets. The key characteristic of these sheets is that only wound, not stacked, magnetic circuits can be produced.

[0120] These sheets are obtained in the form of ribbons by rapid solidification of a liquid. The alloy is amorphous, that is to say, the atoms constituting it do not exhibit long-range order.

[0121] For certain particular atomic compositions, it will be possible by controlled crystallization of the amorphous alloy to obtain biphasic materials comprising a nanocrystalline phase included in a matrix which remains amorphous.

[0122] Amorphous and nanocrystalline materials exhibit low magnetic anisotropy which can be adapted to the applications targeted by post-quenching heat treatments.

[0123] Their magnetic properties are remarkable: a low coercive field, high permeabilities (impedance or initial), low electromagnetic losses and an ease of controlling the properties by heat treatments.

[0124] Depending on their compositions, these alloys have saturation magnetizations between 0.5 and 1.7 T with magnetostriction values ​​that can be close to 0.2.10 8 up to reach 35.10 6.

[0125] Whatever the architecture chosen, discoid architecture with axial field or cylindrical architecture with radial field, it is the direction of the winding of the toroidal winding and the relationship between the total number of coils on the one hand and the number of pole pairs, the number of phases, the number of coils per pole pair and per phase on the other hand, and the constant k equal to 1, which makes it possible to filter the common mode currents in the magnetic circuit of the stator.

[0126] As shown in [Fig.8], the magnetic fluxes generated by the differential mode currents oppose each other while the magnetic fluxes generated by the common mode currents add up.

[0127] Thus, as the magnetic effects caused by the differential mode currents cancel each other out, the filtering effect has virtually no effect on the differential mode currents, which means that the useful signal which transmits the power from the electronics to the motor is not affected.

[0128] In contrast, the filtering effect opposes an inductance to the common-mode currents, thereby reducing them. In other words, the magnetic effects caused by the common-mode currents add up. Since the common-mode magnetic fluxes of each coil add up, a high inductance opposes the common-mode currents, which tends to reduce them.

[0129] The invention thus has the advantage of not having to add a common mode current filter between the electric motor and the frequency or speed variator.

[0130] Of course, the invention is not limited to the examples just described.

Claims

Demands

1. An electric motor or alternator comprising a rotor (200, 200a, 200b) having p>l pair(s) of magnetic poles (204, 204a, 204b), a stator (100) configured to cooperate at an air gap with said rotor to produce a mechanical force and / or an induced electrical voltage, said stator comprising a plurality N of coils (104, 104B, 104², 104³), characterized in that: - The coils are wound toroidally around the magnetic circuit of the stator, - The coils are wound and energized such that the orthoradial magnetic fluxes of the common-mode currents of each coil add together, so as to obtain a high inductance, to reduce said common-mode currents, - The plurality N of coils satisfies the following equation: N = M x Q x pxk, with: - M: number of phases, k = 1 - Q = number of coils per pole pair and per phase.

2. Electric motor or alternator according to claim 1, characterized in that it admits a cylindrical architecture with radial field.

3. Electric motor or alternator according to claim 2, characterized in that the magnetic circuit (101) of the stator (100) is made up of an assembly of laminations, such as for example a stack of laminations, of Iron-Silicon, Iron-Nickel or Iron-Cobalt alloy.

4. Electric motor or alternator according to claim 3, characterized in that the thickness of said iron-silicon, iron-nickel or iron-cobalt alloy sheets is less than or equal to 0.2 mm, preferably less than or equal to 0.15 mm, even more preferably less than or equal to 0.1 mm.

5. Electric motor or alternator according to claim 2, characterized in that the magnetic circuit (101) of the stator (100) is made up of an assembly of sheets, such as for example a stack of sheets, amorphous or nanocrystalline.

6. Electric motor or alternator according to claim 5, characterized in that the thickness of said amorphous or nanocrystalline sheets is between 10 and 30 microns.

7. Electric motor or alternator according to claim 2, characterized in that the magnetic circuit (101) of the stator (100) is obtained by sintering powders of soft magnetic materials (Soft Magnetic Composites) or alternatively by additive manufacturing.

8. Electric motor or alternator according to claim 1, characterized in that it admits a discoid architecture with single axial air gap, or a double air gap architecture with two rotors (200a, 200b).

9. Electric motor or alternator according to claim 8, characterized in that the magnetic circuit (101) of the stator (100) is made up of a winding of iron-silicon, iron-nickel or iron-cobalt alloy sheets.

10. Electric motor or alternator according to claim 9, characterized in that the thickness of said iron-silicon, iron-nickel or iron-cobalt alloy sheets is less than or equal to 0.2 mm, preferably less than or equal to 0.15 mm, even more preferably less than or equal to 0.1 mm.

11. Electric motor or alternator according to claim 8, characterized in that the magnetic circuit (101) of the stator (100) is made up of a winding of amorphous or nanocrystalline sheets.

12. Electric motor or alternator according to claim 11, characterized in that the thickness of said amorphous or nanocrystalline sheets is between 10 and 30 microns.

13. Electric motor or alternator according to claim 8, characterized in that the magnetic circuit (101) of the stator (100) is obtained by sintering powders of soft magnetic materials (Soft Magnetic Composites) or alternatively by additive manufacturing.

14. Electric motor or alternator according to any one of the preceding claims, characterized in that the magnetic circuit (101) of the stator is notched-free.

15. Use of an inverter-powered electric motor, conforming to any one of the preceding claims, wherein no common-mode current filter is disposed upstream of said motor.

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