EP3235108A2

EP3235108A2 - Electrical machine

Info

Publication number: EP3235108A2
Application number: EP15823351.0A
Authority: EP
Inventors: Abdou Salembere; Yacine AYAD; Samir Guerbaoui
Original assignee: Valeo Systemes de Controle Moteur SAS
Current assignee: Valeo Systemes de Controle Moteur SAS
Priority date: 2014-12-19
Filing date: 2015-12-14
Publication date: 2017-10-25
Also published as: WO2016097564A3; FR3030924A1; FR3030924B1; WO2016097564A2

Abstract

The electrical machine (100) comprises: a stator (102) comprising at least two pairs of stator teeth, a rotor (104) and, for each pair of stator teeth (110, 112, 114, 116), at least one coil (118, 120, 122, 124) wound around a respective stator tooth (110, 112, 114, 116), the coil or coils being intended to generate a magnetic flux spreading from one stator tooth (110, 112, 114, 116) to the other. The electric machine (100) further comprises one or more magnetic flux diversion pieces (130) intended, for each pair of stator teeth (110, 112, 114, 116) and when the coil or coils (118, 120, 122, 124) of the pair of stator teeth (110, 112, 114, 116) is/are generating magnetic flux, to capture a first part (132) of the magnetic flux so that it spreads from one stator tooth (110, 112, 114, 116) to the other avoiding the rotor (104), whereas second part (134) of the magnetic flux spreads from one stator tooth (110, 112, 114, 116) to the other passing via a pair of rotor teeth (126, 128) so as to apply driving torque to the rotor (104).

Description

TITLE

ELECTRIC MACHINE

TECHNICAL AREA

The present invention relates to an electric machine with variable reluctance. More particularly, the invention relates to a variable reluctance machine for application, as an electric motor, in a motor vehicle, in particular for an electric supercharger. The present invention also relates to an electric supercharger for a motor vehicle, comprising such a variable-reluctance electric motor. TECHNOLOGICAL BACKGROUND

It is known to implement an electric supercharger in an air supply circuit of an internal combustion engine of a motor vehicle.

Such an electric supercharger is conventionally implemented in the air intake line of a combustion engine of a motor vehicle, upstream or downstream of a turbocharger. Alternatively, or in addition as described in the French patent application published under the number FR 2 991 725 A1, such a compressor can be implemented on a recirculation line of the exhaust gas of the internal combustion engine.

The electric supercharger conventionally comprises a wheel for compressing the air entering the compressor and an electric motor for driving the wheel in rotation.

Unlike turbochargers, driven by the exhaust gas, the electric supercharger has a very short response time because it works with an electric motor. This makes it possible to increase the torque of the internal combustion engine at low speed, to compensate the response time of the turbocharger and to improve the acceleration of the motor vehicle on which mounted the internal combustion engine equipped with the electric supercharger.

It is known to use, as electric motor of the electric supercharger, a variable reluctance electrical machine comprising:

a stator delimiting an interior space,

a rotor extending in the interior space of the stator and intended to rotate about an axis of rotation,

the stator comprising at least two pairs of stator teeth oposed with respect to the axis of rotation, and the rotor comprising at least one pair of rotor teeth opposite to the axis of rotation,

for each pair of stator teeth, at least one coil wound around a respective stator tooth, the coil or coils of each pair of stator teeth being intended to generate a magnetic flux propagating from a stator tooth of the pair to the stator tooth; 'other.

A conventional variable reluctance electric motor has the disadvantage of providing a motor torque that varies greatly undulating according to the angular position of the rotor. This variation in engine torque involves mechanical vibrations that make the electric motor noisy, which can affect the comfort of the driver of the motor vehicle.

In addition, particularly because of the speed at which such an electric machine is used, such a compressor is noisy, that is to say that it produces significant noise vibrations in the frequency range of 20 Hz to 20,000. Hz.

One possible solution to overcome this problem is to control the phase currents to avoid magnetic flux peaks. However, this solution requires the implementation of complex control strategies.

The object of the invention is to propose an electrical machine configuration with variable reluctance making it possible to limit the peaks of magnetic flux in the rotor and therefore the noise of the electric machine.

SUMMARY OF THE INVENTION For this purpose, there is provided an electric machine, in particular an electric motor, with variable reluctance comprising: a stator delimiting an interior space,

for each pair of stator teeth, at least one coil wound around a respective stator tooth, the coil or coils of each pair of stator teeth being intended to generate a magnetic flux propagating from a stator tooth of the pair to the stator tooth; 'other,

characterized in that the electric machine further comprises:

one or more magnetic flux bypass pieces intended, for each pair of stator teeth, and when the coil or coils of the pair of stator teeth generate a magnetic flux, to capture a first portion of the magnetic flux so that it propagates itself; a stator tooth to another avoiding the rotor, while a second portion of the magnetic flux propagates from one stator tooth to the other through a pair of rotor teeth to apply a motor torque to the rotor.

Optionally, the one or more bypass pieces comprise a cylinder attached to end faces of the stator teeth.

Optionally also, the electric motor comprises at least one pair of rotor teeth and the one or more bypass pieces comprise a cylinder attached to end faces of the rotor teeth.

Also optionally, the at least one branch part comprises bypass pieces connecting side faces of two successive stator teeth, respectively.

Also optionally, the at least one branch part comprisesdiver parts connecting side faces of two successive rotor teeth respectively.

Also optionally, the at least one branch piece is made of ferromagnetic material. Also optionally, the at least one branch piece has a maximum relative permeability of between 500 and 2,000.

The invention further relates to an electric supercharger for a motor vehicle, comprising an electric motor according to the invention. DESCRIPTION OF THE FIGURES

An embodiment of the invention will now be described by way of example only, with reference to the following figures.

Figure 1 is a sectional view of a first electric motor according to the invention.

Figure 2 is a sectional view of a second electric motor according to the invention.

Figure 3 is a sectional view of a third electric motor according to the invention.

Figure 4 is a sectional view of a fourth electric motor according to the invention.

DETAILED DESCRIPTION

With reference to FIG. 1, a first electric motor 100 according to the invention will now be described.

The electric motor 100 is an electric motor with variable reluctance.

The electric motor 100 comprises a stator 102 and a rotor 104 intended to rotate relative to the stator 102 about an axis of rotation 106.

The stator 102 comprises a frame 108 having a cylindrical shape about the axis of rotation 106.

The stator 102 further comprises at least two pairs of stator teeth 110, 114 and 112, 116 projecting radially from the frame 108 towards the axis of rotation 106. The stator teeth 110, 112, 114, 116 are distributed angularly. in a uniform manner about the axis of rotation 106, and each pair has two stator teeth 110, 114 and 112, 116 opposite one another relative to the axis of rotation 106. The two teeth stator 110, 114 and 112, 116 of the same pair are symmetrical with respect to the axis of rotation 106. In addition, each stator tooth 110, 114, 112, 116 is symmetrical with respect to a median line passing through the axis of rotation 106.

The motor 100 further comprises, for each pair of stator teeth 110, 114 and 112, 116, at least one coil 118, 120, 122, 124 wound around one of the stator teeth 110, 112, 114, 116 of the pair . In the example described, a coil 118, 120, 122, 124 is wound around each stator tooth 110, 112, 114, 116. The coil or coils 118, 120, 122, 124 of each pair of stator teeth 110, 112 , 114, 116 are intended to be traversed by a phase current and thus to generate a magnetic flux propagating from a stator tooth of the pair to the other.

The rotor 104 extends into the stator 102 and has at least one pair of rotor teeth 126, 128 projecting radially away from the axis of rotation 106. The rotor teeth 126, 128 are uniformly distributed around the rotor. axis of rotation 106, and each pair has two rotor teeth 126, 128 opposite one another relative to the axis of rotation 106.

In general, the motor preferably has more pairs of stator teeth than pair (s) of rotor teeth. For example, the motor has between two and six pairs of stator teeth, and very preferably three pairs of stator teeth.

The stator 102 and the rotor 104 are made of ferromagnetic material and preferably have a maximum relative permeability greater than 10,000.

The electric motor 100 further comprises a bypass piece 130 of magnetic flux. In the example described, the bypass piece 130 is a cylinder extending around the axis of rotation 106, in an air gap between the stator teeth and the rotor teeth. Preferably, the cylinder is circularly centered and centered on the axis of rotation 106. The branch piece 130 is fixed to an end face of each stator tooth 110, 112, 114, 116. Thus, the bypass piece 130 is at the front of the coils 118, 120, 122, 124, that is to say the side of the coils 118, 120, 122, 124 which is opposite the frame 108.

The branch piece 130 is made of ferromagnetic material and preferably has a maximum relative permeability of between 500 and 2000.

The operation of the electric motor 100 will now be described. When a phase current is generated in the coil or coils of a pair of stator teeth 110, 114 or 112, 116, this phase current generates a magnetic flux propagating from a stator tooth 110 or 112 of the pair to the other stator tooth 114 or 116 of the pair.

The branch piece 130 captures a first portion 132 of the magnetic flux so that this first portion 132 propagates a stator tooth 110 or 112 of the pair to the other avoiding the rotor 104. At the same time, a second portion 134 magnetic flux propagates from a stator tooth 110 or 112 of the pair to the other through the rotor 104. The second portion 134 of magnetic flux passing through the rotor 104 applies a motor torque to the latter having a tendency to make aligning the pair of rotor teeth 126, 128 with the pair of stator teeth 110, 114 or 112, 116 considered.

Thus, by successively controlling the supply of the coils of each pair of stator teeth 110, 114 and 112, 116, it is possible to rotate the rotor 104, the torque being produced by the tendency of the rotor 104 to position itself so that the reluctance between a stator tooth and a rotor tooth is minimum, that is to say that the gap between these rotor and stator teeth is minimal.

As is known per se, the magnetic flux loops back through the frame 108 of the stator 102.

Due to the presence of the bypass piece 130, a portion 132 of the magnetic flux generated by the coil or coils does not pass through the rotor 104. The proportion of the first portion 132 of magnetic flux with respect to the second portion 134 flux magnetic depends on the intensity of the magnetic flux and thus the current in the coils. Generally, when the magnetic flux is low, the first portion 132 represents only a small fraction of the magnetic flux. On the other hand, when the magnetic flux is strong, certain parts of the rotor 104 can saturate and increase the reluctance of the rotor 104, so that a larger fraction of the magnetic flux passes into the first part 132. Thus, the part of derivation 130 makes it possible to reduce the peaks of magnetic flux passing through the rotor 104 and thus the torque peaks applied to the rotor 104. As a result, the mechanical vibrations of the electric motor 100 are reduced. Preferably, the bypass piece 130 is configured not to capture on average more than 5% of the magnetic flux, but can reach punctually and / or locally peak a flux uptake of 20% to 30%.

With reference to FIG. 2, a second electric motor 200 according to the invention will now be described.

The elements common with the electric motor 100 of Figure 1 will be identified by the same reference signs and will not be described again.

The electric motor 200 comprises, in place of the bypass piece 130 of Figure 1, a magnetic flux bypass part 202 which is a cylinder extending around the axis of rotation 106, in an air gap between the teeth. stator and rotor teeth. The branch piece 202 is attached to an end face of each rotor tooth 126, 128.

The operation of the electric motor 200 is similar to that of the electric motor 100.

With reference to FIG. 3, a third electric motor 300 according to the invention will now be described.

The electric motor 200 comprises, in place of the bypass piece 130 of FIG. 1, several bypass pieces 302, 304, 306, 308 each having a cylindrical wall shape and connecting each of the side faces of two stator teeth 110 respectively. , 112, 114, 116 successive. Thus, the bypass pieces 302, 304, 306, 208 are attached to these side faces in front of the coils 118, 120, 122, 124, that is to say on the side of the coils 118, 120, 122, 124 which is the opposite of box 108.

With reference to FIG. 4, a fourth electric motor 400 according to the invention will now be described.

The electric motor 200 comprises, in place of the bypass piece 130 of FIG. 1, several bypass pieces 302, 304, 306, 308 each having a cylindrical wall shape and connecting each of the lateral faces of respectively two rotor teeth 126 , 128 successive. The present invention is not limited to the embodiments described above, but is instead defined by the following claims. It will be apparent to those skilled in the art that modifications can be made.

In particular, the bypass parts of several of the embodiments can be combined within the same electric motor.

In addition, even if the embodiments concerned electric motors, the invention can also be applied in electric generators.

Furthermore, the terms used in the claims should not be understood as limited to the elements of the embodiments described above, but should instead be understood as covering all the equivalent elements that the skilled person can deduce from his knowledge. General.

Claims

Electric machine (100; 200; 300; 400), in particular electric motor, with variable reluctance comprising:

a stator (102) delimiting an interior space,

a rotor (104) extending in the interior space of the stator (102) and intended to rotate about an axis of rotation,

the stator having at least two pairs of stator teeth (110, 112, 114, 116) oppositely to the axis of rotation, and the rotor having at least one pair of rotor teeth (126, 128) opposite to the 'rotation axis,

for each pair of stator teeth (110, 112, 114, 116), at least one coil (118, 120, 122, 124) wound around a respective stator tooth (110, 112, 114, 116), the the coils of each pair of stator teeth (110, 112, 114, 116) being for generating a magnetic flux propagating from one stator tooth (110, 112, 114, 116) of the pair to the other, characterized in the electric machine (100) further comprises:

one or more magnetic flux bypass pieces (130; 202; 302; 304; 306; 308; 402; 404) for each pair of stator teeth (110,112,114,116) and when the one or more coils (118, 120, 122, 124) of the pair of stator teeth (110, 112, 114, 116) generate a magnetic flux, sensing a first portion (132) of the magnetic flux to propagate a tooth stator (110, 112, 114, 116) to the other avoiding the rotor (104), while a second portion (134) of the magnetic flux propagates from a stator tooth (110, 112, 114, 116) to the other passing through a pair of rotor teeth (126, 128) to apply motor torque to the rotor (104).

An electrical machine (100) according to claim 1, wherein the at least one branch piece includes a cylinder (130) attached to end faces of the stator teeth (110, 112, 114, 116).

An electrical machine (200) according to claim 1 or 2, wherein the at least one branch piece includes a cylinder (202) attached to end faces of the rotor teeth (126, 128).

4. Electrical machine (300) according to any one of claims 1 to 3, wherein the one or more bypass pieces comprise bypass pieces (302, 304, 306, 308) connecting side faces of respectively two stator teeth ( 0, 112, 114, 116).

An electrical machine (400) according to any one of claims 1 to 4, wherein the rotor (104) has rotor teeth (126, 128) and wherein the at least one breaker member includes breaker members (402). , 404, 406, 408) connecting side faces of respectively two successive rotor teeth (126, 128).

An electrical machine (100; 200; 300; 400) according to any one of claims 1 to 5, wherein the at least one branch piece (130; 202; 302,304;

306, 308; 402, 404) are made of ferromagnetic material.

An electrical machine (100) according to claim 6, wherein the one or more bypass members (130; 202; 302,304,306,308; 402,404) have a maximum relative permeability of between 500 and 2,000.

An electric supercharger for a motor vehicle, comprising an electric motor (100; 200; 300; 400) according to any one of claims 1 to 8.