Assembly for motor vehicles, comprising a transmission system

Abstract

Title: Assembly for a motor vehicle, comprising a transmission system. The invention relates to an assembly for a vehicle, in particular a motor vehicle, comprising: a transmission system with at least two speeds, a synchronous electric machine (20) with permanent magnets, in particular with 5 pole pairs, comprising a stator (22) and a rotor (21) provided with permanent magnets (28), coupled to the transmission system with at least two speeds, the electric machine (20) being configured to operate over a rated speed range and the permanent magnets of the rotor being configured such that the electric machine (20) exhibits, within the rated speed range, a magnetic flux along the direct axis D (PhiD) greater than the magnetic flux along the quadrature axis Q (PhiQ) by a factor of at least 1.5, in particular by a factor of at least 2. Figure for the abstract: Fig. 2

Description

Title of the invention: Assembly for a motor vehicle, comprising a transmission system

[0001] The invention relates in particular to an assembly for a vehicle, in particular a motor vehicle, comprising a transmission system with at least two speeds.

[0002] In the field of motor vehicles (electric vehicles), the use of single-speed transmission systems is well known. These single-speed transmission systems allow the power of the electric motor to be transmitted to the wheels without the need for gear changes. One difficulty associated with these systems is that this type of transmission must ensure optimal performance at different speeds and load conditions. This can lead to high vehicle energy consumption over driving cycles.

[0003] The invention aims in particular to remedy the aforementioned problems.

[0004] The invention thus relates to an assembly for a vehicle, in particular a motor vehicle, comprising: - a transmission system with at least two speeds, - a permanent magnet synchronous electric machine, in particular with 5 pole pairs, comprising a stator and a rotor equipped with permanent magnets, coupled to the transmission system with at least two speeds, the electric machine being configured to operate over a rated speed range and the permanent magnets of the rotor are configured so that the electric machine has, in the rated speed range, a magnetic flux in the direct axis D (PhiD) greater than the magnetic flux in the quadrature axis Q (PhiQ) by a factor of at least 1.5, in particular by a factor of at least 2.

[0005] The transmission system, with at least two speeds, allows the system to change between two different speed ratios, depending on the operating point demand. At low speeds (for example, for starting), a higher gear ratio can provide greater torque, while at high speeds (for example, for cruising), a lower gear ratio can improve energy efficiency. When the speed demand increases, the transmission shifts to the second gear (lower gear). This allows the machine to continue operating at rotational speeds that remain within a low speed range. The electric machine is optimized for low speeds.

[0006] In other words, this allows all points to be moved towards lower speeds thanks to the two speed ratios to work over a more restricted speed range. In this case, it is no longer necessary to optimize the electric machine at high speeds, and in particular, it is not necessary to configure the electric machine for high-speed flux deflux. The electric machine only needs to be optimized at low speeds, preferably within a speed range of 0 to 6000 rpm.

[0007] The transmission system with at least two speeds allows operation within a narrower speed range (at low speeds). The invention enables higher efficiency within this narrower speed range.

[0008] Under these conditions, thanks to the invention, it is possible to provide the electric machine with more pole pairs, for example 5 pole pairs, instead of the 4 pole pairs usually used. This allows for higher torques.

[0009] In general, the invention allows the optimization of an electric machine for a transmission system with at least two speeds in order to reduce the vehicle's consumption over driving cycles compared to a single-speed transmission, while maintaining equivalent performance and taking into account cost optimization.

[0010] Two gears in the gearbox allow the electric motor to be optimized to operate within a narrower speed range. In addition to reducing the size of the electric motor, improved efficiency over the driving cycle results in benefits such as a smaller battery size, reduced battery cost / weight, increased range for the same battery size, and a lower carbon footprint.

[0011] In the present invention, the transmission system may be two-speed, or alternatively, have a number of speeds greater than or equal to 3. In all cases, the ratios in the gearbox allow the optimization of the electric machine to operate in a narrower speed range.

[0012] According to one aspect of the invention, the electric machine is configured to deliver a torque of up to approximately 200 or 300Nm over the nominal speed range.

[0013] We have the relation Tq=k*(PhiD*IQ-PhiQ*ID) in which

[0014] Tq is the electromagnetic torque generated by the electrical machine,

[0015] k is a constant of the machine which depends on physical and geometric parameters of the machine,

[0016] PhiD is the magnetic flux in the direct axis D,

[0017] IQ is the component of the current in the quadrature axis Q,

[0018] PhiQ is the magnetic flux along the quadrature axis Q,

[0019] ID is the component of the current in the direct axis D.

[0020] In the present invention, the aim is to minimize the magnetic flux along the quadrature axis Q (PhiQ) and maximize the magnetic flux along the direct axis D (PhiD). The product of the torque is primarily derived from the PhiD component (and the IQ current). This allows for optimization of the torque (torque efficiency) and efficiency according to the operating conditions.

[0021] Preferably, the rotor comprises, for each pole, permanent magnets placed in housings in the rotor body.

[0022] The magnets are thus inserted into the rotor, and are also called buried magnets. This technology is called internal permanent magnet (IPM for Interior Permanent Magnets).

[0023] Preferably, the rotor comprises, for each pole, a pair of main permanent magnets arranged at a non-zero angle to a radius of the rotor. In each pole, the two magnets of the pair move towards each other as they approach the center of the rotor. The two main permanent magnets of each pole are thus arranged in a V, with the point of the V facing the center of the rotor.

[0024] According to one aspect of the invention, the two main magnets, adjacent to two successive poles, are placed in respective housings in the rotor body, these housings being arranged so as to approach each other towards the outer periphery of the rotor. These housings are separated, at the location where they are closest (namely at a location substantially closer to the outer periphery of the rotor than to the center of the rotor), by a non-zero gap d.

[0025] According to one aspect of the invention, the two adjacent housings are symmetrical to each other with respect to a plane of symmetry which contains the axis of rotation of the rotor.

[0026] According to one aspect of the invention, the two adjacent housings have, in cross-section, an overall rectangular shape to receive the main permanent magnets which have a rectangular cross-section.

[0027] According to one aspect of the invention, the spacing d is chosen to be greater than or equal to the thickness of a sheet of a bundle of sheets which forms the rotor body.

[0028] According to one aspect of the invention, the spacing d between the two adjacent housings is smaller than the angular opening of a notch in the stator.

[0029] According to one aspect of the invention, the gap d is chosen to be between 0.2 mm and 2 mm, preferably between 0.25 mm and 0.35 mm.

[0030] In the invention, we seek to have, at the level of the quadrature axis Q, in order to reduce the flux PhiQ to the maximum, the spacing d between the main permanent magnets as small as possible.

[0031] According to one aspect of the invention, the two adjacent housings (respectively of two successive poles) each form, with a radius of the rotor, an angle Mag_anglel between 5° and 80°, being for example between 10° and 45°.

[0032] Preferably, the two housings of the main permanent magnets are not parallel to each other.

[0033] According to one aspect of the invention, each housing is spaced from the machine by an air gap (between the rotor and the stator) of a distance b which is in particular between 0.2 mm and 2 mm, preferably between 0.25 mm and 0.35 mm.

[0034] For example, the rotor comprises, for each of the poles, in addition to the main permanent magnets, at least one pair of secondary magnets.

[0035] According to one aspect of the invention, for each of the poles, the two secondary permanent magnets are arranged between the two main permanent magnets.

[0036] According to one aspect of the invention, each secondary permanent magnet has a rectangular cross-section.

[0037] According to one aspect of the invention, the large side of this rectangular cross-section of the secondary permanent magnet makes an angle with a radius of the rotor, which is between 0° and 20°.

[0038] According to one aspect of the invention, each secondary permanent magnet is for example aligned with a radius of the rotor.

[0039] According to one aspect of the invention, the two secondary permanent magnets are arranged symmetrically with respect to the plane of symmetry of the two main permanent magnets.

[0040] According to one aspect of the invention, the main permanent magnets have a larger cross-section than the cross-section of the secondary permanent magnets.

[0041] According to one aspect of the invention, the secondary permanent magnets are arranged just as close to the air gap as the main permanent magnets, or even closer than the main permanent magnets.

[0042] The invention further relates to a permanent magnet synchronous machine configured to form an assembly as above described.

[0043] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and several illustrative and non-limiting examples of embodiments given with reference to the accompanying schematic drawings on the other hand, in which:

[0044] [Fig-1] Fig. 1 represents very schematically an assembly according to an example of realization of the invention;

[0045] [Fig.2] The [Fig.2] is a cross-sectional view of an electrical machine of the whole of the [Fig.1];

[0046] [Fig.3] The [Fig.3] is a graph which represents the different levels of losses as a function of machine speed and torque.

[0047] The features, variants and different embodiments of the invention can be combined with each other in various combinations, provided that they are not incompatible or mutually exclusive. others. In particular, variants of the invention may be imagined comprising only a selection of features described subsequently in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0048] Figure [1] shows an assembly 100 for a motor vehicle, comprising: - a 10-speed, two-speed transmission system, - a permanent magnet synchronous electric machine 20, here with 5 pole pairs, comprising a stator 22 and a rotor 21 provided with permanent magnets, coupled to the two-speed transmission system 10, the electric machine 20 being configured to operate over a rated speed range of 0 to 6000 rpm, and the permanent magnets of the rotor 21 are configured so that the electric machine 20 has, in the rated speed range, a magnetic flux in the direct axis D (PhiD) greater than the magnetic flux in the quadrature axis Q (PhiQ) by a factor of at least 1.5, in particular by a factor of at least 2.

[0049] In the invention, we thus have: PhiD>1,5PhiQ or PhiD>2PhiQ.

[0050] The two-speed transmission system 10 allows the system to switch between two different speed ratios, depending on the operating point demand. At low speeds (for example, for starting), a higher gear ratio can provide greater torque, while at high speeds (for example, for cruising), a lower gear ratio can improve energy efficiency. When the speed demand increases, the transmission shifts to the second gear (lower gear). This allows the machine to continue operating at rotational speeds that remain within a low speed range. The electric machine 20 is optimized for low speeds.

[0051] In other words, this allows all points to be shifted to lower speeds thanks to the two speed ratios, enabling operation within a narrower speed range. In this case, it is no longer necessary to optimize the electric machine 20 for high speeds, and in particular, it is not necessary to configure the electric machine 20 for high-speed flux reduction. The electric machine 20 only needs to be optimized for low speeds, here within the speed range of 0 to 6000 rpm.

[0052] The two-speed transmission system 10 allows operation within a narrower speed range (at lower speeds). The invention enables higher efficiency within this narrower speed range.

[0053] Under these conditions, thanks to the invention, it is possible to provide the electric machine 20 with more pole pairs, for example 5 pole pairs, instead of the 4 pole pairs usually used. This allows for higher torques.

[0054] In general, the invention allows the optimization of an electric machine 20 for a two-speed transmission system 10 in order to reduce the vehicle's consumption over driving cycles compared to a single-speed transmission, while maintaining equivalent performance and taking into account cost optimization.

[0055] Two gears in the gearbox allow the electric motor 20 to be optimized to operate within a narrower speed range. In addition to reducing the size of the electric motor 20, improved efficiency over the driving cycle results in benefits such as a smaller battery size, reduced battery cost / weight, increased range for the same battery size, and a lower carbon footprint.

[0056] According to one aspect of the invention, the electric machine 20 is configured to deliver a torque of up to approximately 200 or 300 Nm over the nominal speed range.

[0057] We have the relation Tq=k*(PhiD*IQ-PhiQ*ID) in which

[0058] Tq is the electromagnetic torque generated by the electric machine 20,

[0059] k is a constant of the machine which depends on physical and geometric parameters of the machine,

[0060] PhiD is the magnetic flux in the direct axis D,

[0061] IQ is the component of the current in the quadrature axis Q,

[0062] PhiQ is the magnetic flux along the quadrature axis Q,

[0063] ID is the component of the current in the direct axis D.

[0064] In the present invention, the aim is to minimize the magnetic flux along the quadrature axis Q (PhiQ) and maximize the magnetic flux along the direct axis D (PhiD). Torque is generated primarily with the PhiD component (and the current IQ). This allows for optimization of the torque (torque efficiency) and the overall efficiency under the operating conditions.

[0065] The stator 22 comprises a stator body 23 formed by a stack of laminations, and including notches 24 for U-shaped conductive pins 25. Instead of these pins, continuous wire windings may be provided.

[0066] The rotor 21 comprises, for each pole, a pair of main permanent magnets 28 arranged at a non-zero angle with respect to a radius of the rotor. In each pole, the two magnets of the pair move towards each other as they move towards the center of the rotor. The two main permanent magnets 28 of each pole are thus arranged in a V shape, with the point of the V facing the center of the rotor. In [Fig. 2], only half of each pole is shown. The complete pole is obtained by adding the mirror image of the sector between the D and Q axes.

[0067] The two main magnets 28, adjacent to two successive poles, are placed in respective housings 29 of the rotor body 30, these housings being arranged so as to approach each other towards the outer periphery of the rotor. These housings 29 are separated, at the location where they are closest (namely at a location substantially closer to the outer periphery of the rotor than to the center of the rotor), by a non-zero gap d.

[0068] The two neighboring housings 29, and therefore the two neighboring main magnets 28, are symmetrical to each other with respect to a plane of symmetry SP which contains the axis of rotation of the rotor 21.

[0069] The two neighboring housings 29 have, in cross-section, an overall rectangular shape to receive the main permanent magnets 28 which have a rectangular cross-section.

[0070] The spacing d is chosen to be greater than or equal to the thickness of a sheet of a bundle of sheets that form the rotor body 30.

[0071] The spacing d between the two neighbouring housings 29 is smaller than the angular opening of a notch 24 of the stator 22.

[0072] The spacing d is chosen to be between 0.2 mm and 2 mm, preferably between 0.25 mm and 0.35 mm.

[0073] In the invention, we seek to have, at the level of the quadrature axis Q, in order to reduce the flux PhiQ to the maximum, the spacing d between the main permanent magnets 28 as small as possible.

[0074] The two neighboring housings 29 each form, with a radius of the rotor 21, an angle Mag_anglel between 5° and 80°, being for example between 10° and 45°.

[0075] The two housings 29 of the main permanent magnets 28 are not parallel to each other, and do not touch each other.

[0076] Each housing 29 is spaced from the air gap (between the rotor 21 and the stator 22) of the machine by a distance b which is in particular between 0.2 mm and 2 mm, preferably between 0.25 mm and 0.35 mm.

[0077] The rotor 21 comprises, for each of the poles, in addition to the main permanent magnets 28, a pair of secondary permanent magnets 32.

[0078] For each of the poles, the two secondary permanent magnets 32 are arranged between the two main permanent magnets 28.

[0079] Each secondary permanent magnet 32 ​​has a rectangular cross-section.

[0080] The long side of this rectangular cross-section of the secondary permanent magnet 32 ​​makes an angle with a radius of the rotor 21, which is between 0° and 20°.

[0081] Each secondary permanent magnet 32 ​​is for example aligned with a radius of the rotor 21.

[0082] The two secondary permanent magnets 32 are arranged symmetrically with respect to the plane of symmetry PS of the two main permanent magnets 28.

[0083] The main permanent magnets 28 have a larger cross-section than the cross-section of the secondary permanent magnets 32.

[0084] The secondary permanent magnets 32 are arranged just as close to the air gap as the main permanent magnets 28, or even closer than the main permanent magnets 28.

[0085] In [Fig.3], the different levels of losses for a group can be seen. powertrain (including in particular the electric machine, inverter and transmission system).

[0086] Reducing energy losses improves the system's efficiency. The x-axis represents the speed of the electric machine 20 and the y-axis represents the torque.

[0087] On the graph in [Fig.3], we see that the operating points of the system are in a reduced speed range, here between 0 and 5000 revolutions / min (rpm), with lower losses.

[0088] It is therefore possible to increase, for example, the number of pole pairs, because there is no longer a problem of defluxing at high speeds (since these high speeds are avoided).

[0089] Example Application:

[0090] First ratio rl = 10.5 : 1 . This ratio is used for situations requiring high torque, such as initial acceleration or driving uphill.

[0091] Second ratio r2 = 4.7727 : 1 . This ratio is used for driving at higher speeds, where the engine can run at a lower speed, thus saving energy.

Claims

Demands

1. Assembly (100) for a vehicle, in particular a motor vehicle, comprising: - a transmission system (10) with at least two speeds, - a permanent magnet synchronous electric machine (20), in particular with 5 pole pairs, comprising a stator (22) and a rotor (21) provided with permanent magnets (28), coupled to the transmission system (10) with at least two speeds, the electric machine (20) being configured to operate over a rated speed range and the permanent magnets of the rotor are configured such that the electric machine (20) has, in the rated speed range, a magnetic flux in the direct axis D (PhiD) greater than the magnetic flux in the quadrature axis Q (PhiQ) by a factor of at least 1.5, in particular by a factor of at least 2.

2. Assembly (100) according to the preceding claim, wherein the rotor (21) comprises, for each pole, a pair of main permanent magnets (28) arranged with a non-zero angle with respect to a radius of the rotor.

3. Assembly (100) according to the preceding claim, wherein the two main magnets (28) adjacent to two successive poles are placed in respective housings (29) of the rotor body, these housings (29) being arranged so as to approach each other towards the outer periphery of the rotor, and these housings are separated, at the location where they are closest, by a gap (d) which is non-zero.

4. Assembly (100) according to the preceding claim, wherein the spacing (d) is chosen to be greater than or equal to the thickness of a sheet of a bundle of sheets that form the rotor body.

5. Assembly (100) according to claim 3 or 4, wherein the gap (d) between the two adjacent housings (29) is smaller than the angular opening of a stator notch, and in particular the gap (d) is chosen to be between 0.2 mm and 2 mm, preferably between 0.25 mm and 0.35 mm.

6. Set (100) according to any one of claims 3 to 5, wherein the two adjacent dwellings (29) are symmetrical to each other with respect to a plane of symmetry which contains the axis of rotation of the rotor, and in particular the two neighboring housings (29) have, in cross-section, a generally rectangular shape to receive the main permanent magnets (28) which have a rectangular cross-section.

7. Assembly (100) according to the preceding claim, wherein the two adjacent housings (29) each form, with a radius of the rotor, an angle Mag_anglel between 5° and 80°, being for example between 10° and 45°.

8. Assembly (100) according to any one of claims 3 to 7, wherein each housing is spaced from the machine by an air gap (between the rotor and the stator) of a distance (b) which is in particular between 0.2 mm and 2 mm, preferably between 0.25 mm and 0.35 mm.

9. Assembly (100) according to any one of claims 2 to 7, wherein the rotor comprises, for each of the poles, in addition to the main permanent magnets (28), at least one pair of secondary permanent magnets (32), and in particular, for each of the poles, the two secondary permanent magnets (32) are arranged between the two main permanent magnets (28).

10. Assembly (100) according to the preceding claim, wherein the larger side of the rectangular cross-section of the secondary permanent magnet (32) makes an angle with a radius of the rotor, which is between 0° and 20°.

11. Assembly (100) according to claim 9 or 10, wherein the main permanent magnets (28) have a cross-section greater than the cross-section of the secondary permanent magnets (32).

12. Permanent magnet synchronous machine configured to form an assembly (100) according to any one of the preceding claims, in particular with 5 pole pairs.

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