Rotor of an electric rotating machine and electric rotating machine including said rotor

Abstract

Provision of rotors. A rotor (10) of an electric motor includes a number of poles (10) arranged circumferentially about the rotor, each pole having a first set (S1) near the rotor outer edge (32) and a second set (S2) further from the rotor outer edge (32). The first (S1) and second (S2) sets are symmetrical about a d-axis (A). Each symmetrical portion (S2.1, S2.2) in the second set (S2) has two opposite ends (40, 44, 42, 46) terminating respectively in an outer flux barrier (40, 42) near the outer edge (32) and an opposite inner flux barrier (44, 46), both inner flux barriers (44, 46) separated from each other by an arrangement comprising two radially extending inner bridges (48, 50) flanked by a radially extending central flux barrier (52) aligned along the d-axis (A).

Description

[Technical Field]

[0001] The present disclosure relates to a rotor for an electric rotating machine and an electric rotating machine including such a rotor. [Background technology]

[0002] Increasing demand for vehicles has led to rapid development in the automotive industry and a shift toward vehicle electrification. Recently, hybrid and fully electric vehicles have gained increasing interest due to their low or zero emissions. These types of vehicles may employ various types of electric machines in their drivetrains. Permanent magnet synchronous motors (PMSMs) have proven to be the most common type due to their high power and torque density, high efficiency over a wide speed range, compact design, and easy maintenance.

[0003] Designing a PMSM is not an easy task, and issues that arise during the design phase must be carefully addressed and addressed. The stator of a PMSM has three-phase windings, and its coils are excited with a sinusoidally time-varying current, thereby generating a rotating magnetic field of constant magnitude. Meanwhile, permanent magnets in the PMSM's rotor generate a static magnetic field that rotates with the rotor's rotation. The interaction of the two magnetic fields in the air gap between the stator and rotor results in the generation of electromagnetic torque. There are various types of PMSMs, such as surface PMSM (SPMSM), interior PMSM (IPMSM), and PM-assisted synchronous reluctance machine (PMaSynRM).

[0004] An IPMSM is a type of motor with permanent magnets embedded inside the rotor core laminations. A major consideration during the design phase of an IPMSM is the rotor pole shape. The placement of the magnets in the rotor and the design of their respective pockets, including flux barriers, have been found to be important in achieving high torque output with reduced torque ripple and cogging torque. However, some other aspects must be taken into consideration when designing the rotor pole shape.

[0005] Another major consideration in the design phase of an IPMSM is the mechanical stability and strength of the rotor. PMSMs have a wide speed range, and at high rotational speeds, centrifugal forces become very large, causing high mechanical stresses on the rotor. Therefore, the rotor should have sufficiently high mechanical strength to withstand the centrifugal forces. Therefore, this mechanical aspect should be taken into consideration when designing the rotor poles.

[0006] CN106329770A discloses an electric motor with a rotor pole configuration made of one or more magnetic layers arranged radially from the outer edge of the rotor to the inside of the rotor. Each magnetic layer comprises one or more permanent magnets arranged in slots with various possible configurations, and includes bridges separating the magnets of the magnetic layers (e.g., L-shaped). However, this rotor pole configuration can be improved in terms of mechanical strength and motor power output.

[0007] It is therefore desirable to remedy at least one of the above deficiencies. Summary of the Invention

[0008] In accordance with the objectives of the present disclosure, a rotor of an electric rotating machine may be configured to exhibit strong mechanical performance to withstand centrifugal forces that arise during rotation of the rotor, particularly at high rotational speeds.

[0009] To meet this objective, the present disclosure proposes a rotor for an electric rotating machine having a novel rotor pole arrangement, the rotor being configured to rotate about a longitudinal axis, the rotor including a plurality of magnetic poles arranged circumferentially relative to the rotor, each magnetic pole comprising at least a first set and a second set having a permanent magnet arrangement and a flux barrier arrangement, the first set being arranged near an outer edge of the rotor, and the second set being arranged radially relative to the longitudinal axis of the rotor farther from the outer edge than the first set; Each pole has the following configuration in a cross section of the rotor relative to the longitudinal axis of the rotor: each of the first and second sets being symmetrical with respect to a d-axis of symmetry extending radially of the magnetic poles and comprising two symmetrical portions located on either side of the axis of symmetry; - each symmetrical section in the second set has two opposite ends terminating respectively in an outer flux barrier of the flux barrier arrangement positioned near the outer edge of the rotor and an inner flux barrier of the flux barrier arrangement positioned farther from the outer edge than the outer flux barrier, the inner flux barriers of both symmetrical sections being separated from each other by an arrangement comprising two radially extending inner bridges flanked by a radially extending central flux barrier aligned along the axis of symmetry.

[0010] The above arrangement with two radially extending inner bridges allows the bridges to be subjected to centrifugal forces parallel to the bridge direction during rotor rotation. The inner bridges are subjected to only tensile stresses, rather than a combination of tensile and bending stresses. This inner bridge configuration contributes to improved mechanical properties of the entire rotor pole arrangement. Furthermore, an inner bridge configuration with two bridges, each with a width d, rather than a single 2d-wide inner bridge configuration results in a more uniform stress distribution locally in the bridge area, which also results in lower stresses throughout the pole arrangement. This also reduces magnetic flux leakage relative to a single 2d-wide inner bridge configuration, thereby allowing a greater portion of the magnetic flux to contribute to the power output, which may result in improved power output of the electric rotating machine.

[0011] According to a further possible aspect, each of the two radially extending inner bridges extends laterally in a direction perpendicular to the radial direction by a dimension lying in a range between 0.5 mm and 1.2 mm depending on the rotor dimension, the rotor dimension or size (e.g. outer diameter) determining the amount of centrifugal force during rotation, therefore larger rotor diameters require wider bridge dimensions than smaller rotor diameters, this bridge dimension being minimized according to the mechanical stress limits allowed by the material; the permanent magnet arrangements of the first set S1 are substantially V-shaped or linear and the permanent magnet arrangements of the second set S2 are substantially U-shaped or V-shaped; the permanent magnet arrangement in each symmetrical portion of the second set comprises first and second permanent magnets extending continuously along a first direction inclined relative to the radially extending axis of symmetry and a second direction inclined relative to the first direction, respectively, so that the two magnets of both symmetrical portions together form a U-shape; each inner flux barrier in the second set radially expands as it extends along the first direction from an adjacent first permanent magnet toward the radially extending inner bridge, each inner flux barrier including a radially aligned first outer end and an opposite second inner end at the expanding portion of each inner flux barrier, the first outer end being closer to an outer edge of the rotor than the second inner end; a radially extending central flux barrier separated from a second set of inner flux barriers by two radially extending inner bridges, the central flux barrier extending a radial distance that is substantially the same as the radial distance between a first outer end and an opposite second inner end of each inner flux barrier; each outer flux barrier in the second set extends along a second direction from an adjacent second permanent magnet toward an outer edge of the rotor and terminates in an end including a side edge that extends along the circumference of the rotor away from the first set; each symmetrical portion in the first set has two opposite ends, the outer ends terminating in an outer flux barrier of the flux barrier arrangement located near an outer edge of the rotor; each outer flux barrier in the first set extends circumferentially in a nose-shaped configuration having a first side or nose bridge extending parallel to the outer edge of the rotor from a first outer end or top of the nose to an opposite second outer end or tip of the nose, and a second side or nose base extending away from the outer edge from the second end towards a third inner end, the second outer end being located farther from the permanent magnet arrangement than the first outer end; this configuration may also apply when the first set is substantially straight and not V-shaped; - the permanent magnet arrangement in each symmetrical portion of the first set includes permanent magnets extending along a first direction inclined relative to the radially extending axis of symmetry, the permanent magnets of both symmetrical portions together forming a V-shape; each outer flux barrier in the first set extends from an adjacent permanent magnet toward an outer edge of the rotor along a direction oblique to the direction of extension of the adjacent permanent magnet; each symmetrical portion of the first set has an outer end and an opposite inner end separated from each other by a radially extending bridge aligned along the axis of symmetry; each outer flux barrier for each of the first and second sets is not separated from the permanent magnet arrangement of the associated set; the outer bridges are disposed between an outer edge of the rotor and each outer flux barrier for each of the first and second sets, each outer bridge of the second set extending a greater radial distance between the outer edge of the rotor and each outer flux barrier than for each outer bridge of the first set.

[0012] A second object of the present disclosure is to propose an electric rotating machine comprising a rotor as briefly defined above.

[0013] Here, the features and advantages described above with respect to the rotor also apply to the electrical rotating machine and will not be repeated.

[0014] A third object of the present disclosure is to propose a vehicle equipped with an electric rotating machine as briefly defined above. [Brief explanation of the drawings]

[0015] The present invention may be better understood, and numerous other objects and advantages thereof will become apparent to those skilled in the art by reference to the accompanying drawings, in which like reference numerals refer to like elements in the several views. [Figure 1] FIG. 1 is a schematic representation of a cross section of an electric rotating machine according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a partially enlarged view of the rotor pole arrangement of the rotor of FIG. [Figure 3] FIG. 3 is a schematic, partially enlarged view of one of the two symmetrical portions in the first set S1 of FIG. [Figure 4] FIG. 4 is a partial enlarged view of a rotor pole arrangement according to another embodiment of the present disclosure. [Figure 5] FIG. 5 is a partial enlarged view of a rotor pole arrangement according to a further embodiment of the present disclosure. [Figure 6] FIG. 6 is a partial enlarged view of a rotor pole arrangement according to yet a further embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0016] 1, an electric rotating machine 10 (e.g., a motor) for, for example, a vehicle, according to an embodiment of the present disclosure includes a conventional type stator 20 and rotor 30. Such an electric motor may be embodied in a hybrid vehicle or a BEV.

[0017] The electric rotating machine may be a permanent magnet synchronous motor, or PMSM, for example, one of the following types: interior PMSM (IPMSM) and PM auxiliary synchronous reluctance machine (PMaSynRM).

[0018] The stator 20 and rotor 30 cooperate functionally in the usual way. The stator 20 has three-phase windings wound thereon. The coils of the three-phase windings are supplied with time-varying sinusoidal currents, each with a time-shifted phase, and are therefore excited. This arrangement generates a rotating magnetic field of constant magnitude. The rotor 30 includes permanent magnets that generate a static magnetic field that rotates about its axis with the rotor's rotational movement. The two magnetic fields thus generated interact with each other in the air gap between the stator and rotor, thereby generating an electromagnetic torque.

[0019] More specifically, the rotor 30 comprises a plurality of magnetic poles, and as shown in the preferred embodiment of FIG. 1 , comprises eight poles P that are identical to one another and each represent a possible configuration or shape herein. However, rotor pole arrangements having different numbers of poles (e.g., two, four, six, etc.) may alternatively be envisioned. In the cross section of FIG. 1 , the poles P or rotor pole regions or areas are angularly spaced about the rotor's longitudinal axis X (about which the rotor is configured to rotate), with each pole flanked by two other adjacent poles that are angularly spaced about the axis X. As depicted in FIG. 1 , a central opening O may be provided in the rotor to accommodate a rotor shaft (not shown) of axis X to which the rotor may be rotatably mounted.

[0020] In this embodiment, the rotor 30 may be formed of a stack or lamination of rotor plates, which may be uniform or non-uniform and may be secured together by conventional methods, such as gluing, welding, etc. The rotor laminations may be made of a magnetizable material such as e-steel. The rotor plates each exhibit a particular configuration or shape that defines the rotor pole geometry, described below.

[0021] The cross section of Figure 2 shows an enlarged view of a possible configuration or shape for one pole P of rotor 30 of Figure 1. The other poles circumferentially disposed about the rotor have the same configuration or shape.

[0022] As depicted in Figure 2, pole P represents an angular segment of the rotor of Figure 1 bounded by an outer edge 32 (outer circle or diameter) that defines the rotor's exterior contour, and an opposing inner edge 34 (inner circle or diameter) that defines the rotor's central opening as described above. The outer edge 32 may have recesses or indentations 32a, 32b that locally modify the contour of the outer edge 32 to distribute the magnetic flux in the air gap between the rotor and the stator, thereby smoothing the torque of the rotating machine (rotor). Alternatively, the angular segment boundary may be of any form and may be configured differently, for example with more or fewer recesses or indentations.

[0023] The pole P may have an internal configuration comprising a first set S1 and a second set S2 each having a permanent magnet arrangement and a flux barrier arrangement, meaning that each set is made up of one or more receiving pockets for accommodating permanent magnets and one or more flux barriers. In another embodiment, the pole may comprise more than two sets of the above type.

[0024] 2, the first set S1 is positioned near the outer edge 32 of the rotor, and the second set S2 is positioned farther away from the outer edge than the first set in a radial direction relative to the longitudinal axis X. In other words, the second set S2 is positioned closer to the inner edge 34 than the first set.

[0025] The poles P are symmetrical about a radially extending axis of symmetry A, which corresponds to the d-axis or polar axis of the magnetic poles.

[0026] Each set S1 and S2 is symmetrical with respect to the d-axis A and comprises two symmetrical parts or sections S1.1, S1.2 and S2.1, S2.2, respectively, which are mirror images of each other and located on either side of the axis of symmetry.

[0027] As more specifically depicted in the possible pole configurations of FIG. 2, the first set S1 can be substantially V-shaped, and the second set S2 can be substantially U-shaped. More specifically, the shapes of the first and second sets S1, S2 are determined by the shapes of their permanent magnet configurations. Both the V-shape and the U-shape are open on one side, facing the outer edge 32 of the rotor, while the other, opposite side, faces the central portion and longitudinal axis of the rotor. As can be seen in the drawing, the U-shape is open toward the V-shape and is therefore nested more inwardly on the inside of the corner segment of FIG. 2 than the V-shape, which is positioned closer to the outer portion of the corner segment.

[0028] Other shapes for these sets can be envisioned, as will be described later with reference to Figures 4-6.

[0029] The permanent magnet arrangement of the first set S1 may comprise a total of two permanent magnets M1 and M2, with one permanent magnet in each symmetrical part of the set.

[0030] Figure 3 is an enlarged fragment of Figure 2, showing the symmetrical part S1.1 of the first set S1, which includes the magnet M1.1. The following description applies equally to the other symmetrical part S1.2, which includes the magnet M1.2.

[0031] The permanent magnet M1.1 may extend along a direction D1 that is inclined relative to the radially extending axis of symmetry A, so that the magnets M1.1 and M1.2 of both symmetrical parts S1.1 and S1.2 may together form a V-shape.

[0032] Note that alternatively, magnets M1.1 and M1.2 may be separated along a direction parallel to the main rotor axis.

[0033] The permanent magnet configuration of the second set S2 (FIG. 2) may comprise a total of four permanent magnets with two permanent magnets in each symmetrical part of the set, and each symmetrical part S2.1, S2.2 may include a first permanent magnet M2.1, M2.2 and a second permanent magnet M2.3, M2.4, respectively.

[0034] Overall, the magnets in each set need to be as close as possible to the outer diameter 32 (i.e., as close as possible to the air gap with the stator) to maximize electromagnetic interaction, while at the same time having enough material between the outer diameter 32 and the magnets to provide sufficient mechanical strength to withstand the large centrifugal forces generated at high rotor rotational speeds.

[0035] The first permanent magnet M2.1 (M2.3, respectively) may extend along a first direction D3 inclined with respect to the radially extending axis of symmetry A. The second permanent magnet M2.2 (M2.4, respectively) may extend along a second direction D4 inclined with respect to the first direction D3, so that the two magnets of both symmetrical parts S2.1, S2.2 (i.e., four magnets in total) together form a U-shape. The reason for the inclination between D3 and D4 relies on electromagnetic flux reasons: the magnetic flux needs to be guided into the air gap (towards the outer edge 32), while at the same time the magnet position needs to be kept as close as possible to the edge 32 for efficient interaction with the air gap. The magnets M2.1 and M2.2 can be arranged along two directions D3 and D4, respectively, or alternatively, can be replaced by a larger number of magnets with reduced dimensions, for example, a total of four magnets, arranged along an arch shape approximately defined by these two directions (same for magnets M2.3, M2.4). Alternatively, curved magnets can be used. For example, the second direction D4 can be in the range of 5° to 20° with respect to D3. It should be noted that both extension directions D1 and D3 of the two sets S1 and S2 may or may not be parallel to each other.

[0036] Each symmetrical portion S2.1, S2.2 in the second set S2 has two opposite ends which may terminate in outer flux barriers 40, 42 positioned near the outer edge 32 of the rotor and inner flux barriers 44, 46 positioned farther away from the outer edge 32 than the corresponding outer flux barriers 40, 42, more specifically, near the d-axis A.

[0037] The inner flux barriers 44, 46, located on either side of the d-axis A, are separated from one another laterally along the inner circumference of the rotor by an arrangement comprising two radially extending inner bridges 48, 50 flanked by a radially extending central flux barrier 52 aligned along the d-axis A. As shown in FIG. 2, the central flux barrier 52 may straddle the d-axis A.

[0038] Each of the two radially extending inner bridges 48, 50 has its origin at the center of the rotor and can extend transversely, perpendicular to the radial direction, with a dimension, or width, ranging from 0.5 mm to 1.2 mm depending on the rotor dimensions, particularly its outer diameter, to ensure that the thin bridges can withstand stresses resulting from centrifugal forces during rotor rotation, especially at high rotational speeds. If the dimension is less than 0.5 mm, the mechanical strength is insufficient to withstand the forces resulting from rotor rotation. If the dimension is greater than 1.2 mm, this creates a leakage path for magnetic flux.

[0039] In a given embodiment, the rotor has an outer dimension that is approximately 140 mm, and each inner bridge 48, 50 may have a width of 0.8 mm.

[0040] It should be noted that the width of each of the inner bridges 48, 50 does not necessarily have to be constant all along its length (radially).

[0041] As is typical, a central configuration with two bridges separating the two inner flux barriers 44, 46 from each other (even with a different configuration for the inner flux barriers) allows the two bridges to share the centrifugal loads generated during rotor rotation, thereby resulting in a lower stress distribution in the rotor pole arrangement, particularly in areas where high stresses may occur, such as the outer bridges 54, 56 of the second set S2 (described later) (the outer bridges 72 and 74, described later, are also subject to such centrifugal forces). Because lower stresses occur in the rotor, particularly in the areas of the outer bridges 54, 56 (and in the areas of the outer bridges 72 and 74, described later), the outer bridges 54, 56 can be made thinner, which leads to improved electromagnetic performance of the rotor. A central configuration with two bridges separating the two inner flux barriers provides improved mechanical strength to the rotor pole arrangement and, therefore, to the rotor.

[0042] Furthermore, the proposed configuration with two bridges separating the two inner flux barriers to connect as much of the center or bottom portion of the U-shape as possible (in the area between magnets M2.1 and M2.3) allows for a reduction in magnetic flux leakage from the adjacent permanent magnets M2.1 and M2.3, with the goal of increasing the average torque output from the permanent magnets. In this regard, the inner bridges 48, 50 are designed to be as thin as possible to reduce magnetic flux leakage (wider bridges would result in more magnetic flux leakage from the magnets), while keeping the inner bridges 48, 50 strong enough (and therefore not too thin) to withstand the centrifugal forces generated at high rotor rotational speeds.

[0043] As shown in FIG. 2, the inner flux barriers 44 in the second set S2 may extend radially from the adjacent first permanent magnet M2.1 along the first direction D3 toward the corresponding radially extending inner bridge 48 (the inner flux barriers 46 may extend radially from the adjacent first permanent magnet M2.3 along a direction symmetrical to the d-axis A for magnet M2.3 toward the corresponding radially extending inner bridge 50).

[0044] The following description relates to the inner flux barrier 44 but applies equally to the symmetric inner flux barrier 46.

[0045] More specifically, each inner flux barrier, such as inner flux barrier 44, may include a first outer end 44a and an opposite second inner end 44b at its extension, both of which are aligned in the radial direction along which the flux barrier extends. As shown, the first outer end 44a is closer to the rotor outer edge 32 than the second inner end 44b, and the inner flux barrier terminates in a substantially straight wall 44e connecting the two opposite ends 44a, 44b and aligned in the radial direction of the inner flux barrier (the substantially straight wall 44e forms a lateral side of bridge 48, the other lateral side of which is formed by one outer wall of the adjacent flux barrier 52). In other words, inner flux barrier 44 includes two side walls 44c, 44d that extend from magnet M2.1 to first outer end 44a and second inner end 44b, respectively. 2, sidewall 44d forms a curved shape that begins in the area where the pocket is configured to hold magnet M2.1 and makes a substantial 180° turn before extending radially toward the center of the rotor to second inner end 44b. This curved radially extending portion functions to guide magnetic flux from magnet M2.1 around inner flux barrier 44 and inside bridge 48. The resulting inner flux barrier 44 has the overall shape of a shoe, with sidewall 44c being the heel of the shoe and sidewall 44d being the front of the shoe.

[0046] A radially extending central flux barrier 52, separated from the inner flux barriers 44, 46 by two radially extending inner bridges 48, 50, may extend a radial distance that is substantially the same as the radial distance between the first outer end 44a of the inner flux barrier 44 and the opposite second inner end 44b of the inner flux barrier 44 for each inner flux barrier 44, 46. In this embodiment, it is preferred that the central flux barrier 52 does not extend radially inward and / or outward relative to the inner flux barriers 44, 46 to avoid negative effects on the mechanical and / or electromechanical performance of the rotor poles.

[0047] Also, as depicted in FIG. 2, the radially extending central flux barrier 52 may extend a dimension or width at its center comprised between approximately 2.5 mm and 3.5 mm depending on the rotor dimensions.

[0048] It should be noted that the flux barrier 52 has a substantially flared shape from its innermost disposed end (closer to the rotor's inner edge 34) to its outermost disposed end (away from the rotor's inner edge 34) to follow the shape of the inner flux barriers 44, 46 in order to maintain a constant width for the two radially extending inner bridges 48, 50.

[0049] Each outer flux barrier 40, 42 in each symmetrical portion S2.1, S2.2 of the second set S2 may extend from the adjacent second permanent magnet M2.2, M2.4 towards the outer edge 32 of the rotor through a straight portion 40a, 42a along the second extension direction D4 for magnet M2.2 and along a symmetrical direction relative to the d-axis A for magnet M2.4. The extension or pocket 40a, 42a may extend towards the outer edge 32 by as large a dimension as possible while maintaining sufficient material thickness between the end of the outer flux barrier 40, 42 and the outer edge 32 to ensure sufficient (minimum) centrifugal mechanical performance during rotor rotation.

[0050] 2, each outer flux barrier 40, 42 terminates in an end 40b, 42b that may include a side edge 40b1, 42b1 (e.g., a rounded edge) that extends circumferentially (or tangentially) around the rotor in a direction away from the first set S1. Such a tip shape helps to guide the magnetic flux, thereby improving and optimizing electromagnetic performance.

[0051] Additionally, outer bridges 54, 56 are disposed between the rotor outer edge 32 and the ends 40b, 42b of each outer flux barrier 40, 42. As can be seen, each outer bridge 54, 56 extends along the rotor outer edge 32 with a slight increase in distance or thickness between the rotor outer edge 32 and the corresponding end 40b, 42b away from the first set S1 to have more material in this area for mechanical strength.

[0052] As shown in Figures 2 and 3, each symmetrical portion S1.1 and S1.2 of the first set S1 has two opposite ends 60, 62 and 64, 66, respectively, with the outer end 60 for S1.1 being located near the outer edge 32 of the rotor and the opposite inner end 62 for S1.1 being located farther away from the outer edge 32 (the outer end 64 for S1.2 being located near the outer edge 32 of the rotor and the opposite inner end 66 for S1.2 being located farther away from the outer edge 32).

[0053] Each outer end 60, 64 may terminate in an outer flux barrier 61, 65 for a first set of flux barrier arrangements located near the rotor's outer edge 32. The following description of the outer flux barrier 61 of section S1.1 applies equally to the symmetrical outer flux barrier 65 of section S1.2.

[0054] As shown more particularly in the enlarged view of Figure 3, the outer flux barrier 61 may be nose-shaped and extend circumferentially, i.e., substantially along the rotor edge 32. This nose-shaped outer flux barrier 61 may have a first side 61a or nose bridge that extends parallel to the outer edge 32 from a first outer end 61b or nose top to an opposite second outer end 61c or nose tip. In the present configuration of Figures 2 and 3, the opposite second outer end 61c faces the second set S2 and is located farther from the permanent magnet configuration, i.e., permanent magnet M1.1, than the first outer end 61b.

[0055] The nose-shaped outer flux barrier 61 may also have a second side 61d or nose bottom extending from the second end 61c away from the rotor outer edge 32 towards a third inner end 61e disposed inwardly relative to the first and second outer ends 61b and 61c.

[0056] As shown in this configuration, the nose-shaped outer flux barrier 61 may further extend from the third inner end 61e toward the permanent magnet M1.1 through a third substantially straight side 61f. Side 61f may be slightly offset inward relative to the second side 61d and may extend substantially parallel to the second side 61d in this configuration. Side 61f may be connected to end 61e through a slight slope 61g, which allows end 61e to be connected to the pocket of permanent magnet M1.1 without any sharp angles.

[0057] As depicted in this configuration, the first outer end 61b may be connected to the pocket of the permanent magnet M1.1 through a curved side or portion 61h.

[0058] It should be noted that the overall shape of the outer flux barrier 61 may differ from the nose-shaped shape described above. In particular, sides 61d and 61f do not necessarily have to be parallel to each other. In an alternative embodiment (not shown), side 61d, edge 61e, slight slope 61g, and side 61f may be replaced by a single side without any sharp angles that connects second end 61c to the pocket of permanent magnet M1.1.

[0059] As is common, due to mechanical stresses, smooth, rounded transitions in the flux barrier configurations of each of sets S1 and S2 are preferable to sharp transitions that create stress peaks.

[0060] Overall, the outer flux barrier 61 may extend from the adjacent permanent magnet pocket (containing the magnet M1.1) towards the outer edge 32 of the rotor along a direction D2 inclined with respect to the direction D1 in which the adjacent permanent magnet M1.1 extends, for electromagnetic flux. The magnetic flux needs to be guided towards the air gap (between the rotor and the stator), i.e. towards the outer edge 32, while the magnet position needs to be as close as possible to this edge for efficient interaction with the air gap. It should be noted that the magnet M1.1 may be replaced by two or more magnets arranged along an arch shape, depending on the available space in the area of ​​the set S1 relative to the outer edge 32.

[0061] The direction of extension D4 may or may not be parallel to D2 (see FIG. 3).

[0062] The role of the outer flux barriers is to guide the magnetic flux lines from the surrounding magnets, resulting in a more uniform air-gap magnetic flux density distribution. The design of the outer flux barriers 61 and 65, which have a substantially nose-shaped type extending circumferentially along the rotor outer edge 32 (even if their shape and / or orientation are slightly modified), allows for a more uniform distribution of the radial component of the air-gap magnetic flux density, thereby resulting in lower air-gap reluctance, reduced torque ripple and cogging torque, and higher torque output. Therefore, the reluctance torque generated by the motor's pole configuration (the difference in inductance between the d-axis and q-axis) increases. The configuration of the outer flux barriers, such as the flux barrier 61 with the thin circumferentially oriented tips or ends 61b, 61c (the same applies to the outer flux barrier 65), results in a reduction of the rotor's pole axis (or d-axis) inductance, which leads to a reluctance torque boost.

[0063] As mentioned above, the two inner ends 62 and 66 of sections S1.1 and S1.2, respectively, are separated from each other by a radially extending bridge 70 (FIG. 2) aligned along the axis of symmetry A. The bridge 70 may have a width lying between 0.5 mm and 1.5 mm, depending on the rotor dimensions.

[0064] Each inner end 62, 66 may act as an inner flux barrier.

[0065] Additionally, outer bridges 72, 74 are disposed between the rotor outer edge 32 and a first side of each outer flux barrier 61, 65, e.g., first side 61 a of outer flux barrier 61. As can be seen, each outer bridge 72, 74 extends along the rotor outer edge 32 at a substantially constant radial distance or thickness between the rotor outer edge 32 and the corresponding first side of each outer flux barrier 61, 65.

[0066] It should be noted that each outer bridge 72, 74 needs to be as thin as possible (for magnetic performance), yet thick enough to withstand the bending forces generated by the high rotational speed of the rotor. A minimum thickness of 0.9 mm can be assumed. Given the relatively small thickness of the bridges, a parallel configuration between the edge 32 and the corresponding first side of each outer flux barrier 61, 65 is more appropriate. It should be noted that if bridge 70 were not present in this configuration, the outer bridges 72, 74 would succumb to very large bending forces during rotor operation (rotation).

[0067] For the second set S2, each outer bridge 54, 56 may extend a radial distance between the outer edge 32 of the rotor and the end 40b, 42b of each outer flux barrier 40, 42 that is greater than that of each outer bridge 72, 74 of the first set S1. This can be explained by the following: the mechanical loads acting on the bridges 54 and 56 are higher than those acting on the bridges 72 and 74 of the first set, since there are fewer mechanical connections of the magnet pockets of the second set towards the rotor center (the magnet pockets hold the two magnets M2.1 and M2.2 back to back with no metal between them for part S2.1, and are therefore much larger (the same explanation applies to part S2.2 with magnets M2.3 and M2.4)).

[0068] In both sets S1 and S2, each outer flux barrier of each set may not be separated from the adjacent permanent magnet configurations (i.e., magnet housing pockets) of the associated set. Thus, magnetic flux leakage from the permanent magnets located in adjacent housing pockets is reduced, which contributes to an increase in the magnitude of the magnetic flux density in the air gap between the rotor and the stator, thereby leading to higher torque output. In other words, the outer flux barriers 40 and 42 for S1 extend directly from the adjacent permanent magnets M1.1 and M1.2 or their housing pockets (the outer flux barriers 61 and 65 for S2 extend directly from the adjacent permanent magnets M2.2 and M2.4 or their housing pockets for S2), thereby meaning that there are no intermediate or additional elements or structures, such as bridges, between them.

[0069] It should be noted that the flux barriers of the various sets may be air pockets or may be filled with resin.

[0070] Numerical simulations were performed to demonstrate the advantages offered by a rotor having the rotor pole configuration of Figures 1 and 2 compared to a rotor pole configuration that differs only in the presence of a single wider bridge between two spaced apart wider inner flux barriers in a U-shaped set.

[0071] In a specific numerical example based on the configuration of Figures 1 and 2, for a rotor diameter of 140 mm, the width of each inner bridge 48, 50 is selected to be 0.9 mm, while the width of the single wider bridge of the comparative configuration is 1.8 mm, i.e., overall twice the width of each inner bridge 48, 50.

[0072] Numerical simulations are carried out for example at 17,000 rpm (min -1 This was done by rotating both motors, each equipped with one of the rotor pole configurations described above, at a rotational speed of 1000 rpm, and determining the well-known von Mises stress distribution in the rotor pole configurations in the usual manner.

[0073] Thus, in the rotor pole configuration of FIGS. 1 and 2 , the maximum stresses were observed to be located at the center or bottom of the U-shaped configuration, more specifically along the two bridges 48, 50 and the outer bridges 54, 56 of the U-shaped configuration. More specifically, the maximum von Mises stress can be observed in the area of ​​the two bridges 48, 50, where, in this example, the maximum von Mises stress can reach a value of 385 MPa. The specific geometry of this configuration with two bridges allows for a reduction or mitigation of the overall mechanical stress level throughout the pole configuration, more specifically in all of the outer bridges 72 and 74 (for the first set) and 54 and 56 (for the second set) of the rotor poles. Reducing the stress in the outer bridges allows for thinner outer bridges and closer permanent magnets to the air gap, thereby resulting in better magnetic performance. The two inner bridges 48, 50 are positioned so that they are subjected to tension forces only, or more specifically so that both of their central axes are inclined relative to each other and meet at the centre point of the rotor (pole), which in FIG. 1 represents the rotor axis X.

[0074] In a rotor pole configuration with a single wider bridge between two spaced-apart, wider inner flux barriers in a U-shaped configuration, the maximum stresses are located at the center or bottom of the U-shaped configuration, more specifically, in the area of ​​the single center bridge, as well as in the outer bridges of the U-shaped configuration and in the outer bridges of the V-shaped configuration. However, in this configuration, the maximum von Mises stress can reach a value of 460 MPa in this example, which is much higher (about 20% higher) than the value noted above for the configurations of Figures 1 and 2. In the center or bottom area of ​​the U-shaped configuration, the single wider bridge experiences both tensile and bending forces, rather than just the tensile forces at each of the two inner bridges for the configurations of Figures 1 and 2. Also, in this case, the outer bridge of the U-shaped configuration experiences higher bending forces and, therefore, higher generated stresses than in the configurations of Figures 1 and 2.

[0075] Other rotor pole configurations, such as those shown in Figures 4-6, can be envisioned within the framework of this disclosure. Only the differences relative to the above embodiments are detailed below. All aspects (features, functions, advantages, variations, etc.) not described below carry over from the above description, except where the aspects are mutually exclusive with respect to each other or contradict each other (e.g., everything described above with respect to tilting of magnets M1.1 and M1.2 cannot be applied to non-tilted magnets M'1.1 and M'1.2).

[0076] The rotor pole configuration P' of Figure 4 comprises two sets S'1 and S'2 each having a permanent magnet configuration and a flux barrier configuration. - the permanent magnet arrangement of the first set S'1 is substantially linear, here horizontal, with respect to the poles represented, but generally along a linear axis, with the first set magnets M'1.1 and M'1.2 being substantially perpendicular to the d-axis, and the permanent magnet arrangement of the second set S'2 is substantially U-shaped and may have the same characteristics as those described above, in particular comprising four magnets M2.1, M2.2, M2.3 and M2.4.

[0077] The rotor pole configuration P'' of FIG. 5 comprises two sets S''1 and S''2, each having a permanent magnet configuration and a flux barrier configuration. The permanent magnet arrangement of the first set S''1 is substantially V-shaped and may have the same characteristics as those described above, in particular comprising two magnets M1.1 and M1.2. The permanent magnet arrangement of the second set S''2 is substantially V-shaped.

[0078] The V-shaped configuration of the second set S''2 includes two magnets M''2.1 and M''2.2 that are spaced apart from each other and inclined in any part of the set relative to the d-axis. Regarding the permanent magnet configuration of the second set S''2, the two symmetrical parts of the set each end with an inner flux barrier 44'' and 46'' that may differ slightly in shape and size from the corresponding elements 44 and 46 in Figure 2 in order to provide the best flux guidance with an optimal shape and size.

[0079] The second set S''2 includes an arrangement with two radially extending inner bridges 48'' and 50'' flanked by a radially extending central flux barrier 52'' aligned along the polar d-axis of symmetry.

[0080] This arrangement separates the two inner flux barriers 44'' and 46'' from each other, and in the configuration described, the central flux barrier 52'' is wider than the central flux barrier 52 in Figure 2 for optimization (the optimized shape and dimensions depend on the location in the rotor layout).

[0081] The role of the two radially extending inner bridges 48'' and 50'' is the same as that explained above.

[0082] The rotor pole configuration P''' of FIG. 6 comprises two sets S'''1 and S'''2, each having a permanent magnet configuration and a flux barrier configuration. The permanent magnet configuration of the first set S'''1 may be substantially rectilinear and identical to the first set S'1 of FIG. The permanent magnet configuration of the second set S'''2 may be substantially V-shaped and identical to the second set S''2 of FIG.

[0083] With respect to the embodiments and variations described above with reference to Figures 1-3, the permanent magnets of each set of permanent magnet configurations in Figures 4-6 may be rectangular, such as ingots, or may be curved when viewed in cross section transverse to the longitudinal axis of the rotor. The present disclosure includes the following aspects. Example 1. A rotor (30) for an electric rotating machine configured to rotate about a longitudinal axis (X), said rotor including a plurality of magnetic poles (P, P', P'', P''') arranged circumferentially relative to said rotor, each magnetic pole (P, P', P'', P''') comprising at least a first set (S1) and a second set (S2) each having a permanent magnet arrangement and a flux barrier arrangement; the first set (S1) is positioned near an outer edge (32) of the rotor, and the second set (S2) is positioned farther from the outer edge in a radial direction relative to the longitudinal axis of the rotor than the first set; Each magnetic pole (P, P', P'', P''') has the following configuration in a transverse cross section of the rotor relative to the longitudinal axis of the rotor: - each of the first (S1) and second (S2) sets is symmetrical with respect to a d-axis of symmetry (A) extending radially of the magnetic poles and comprises two symmetrical parts (S1.1, S1.2, S2.1, S2.2) located on either side of the axis of symmetry, - each symmetrical section (S2.1, S2.2) of the second set (S2) has two opposite ends (40, 44, 42, 46) terminating respectively in an outer flux barrier (40, 42) of the flux barrier arrangement arranged near the outer edge (32) of the rotor and in an inner flux barrier (44, 46) of the flux barrier arrangement arranged further from the outer edge than the outer flux barrier, the inner flux barriers (44, 46) of both symmetrical sections being separated from each other by an arrangement comprising two radially extending inner bridges (48, 50) flanked by a radially extending central flux barrier (52) aligned along the d-axis of symmetry (A). Example 2. The rotor of example 1, wherein each of the two radially extending inner bridges (48, 50) extends laterally in a direction perpendicular to the radial direction by a dimension within a range of 0.5 mm to 1.2 mm, depending on the rotor dimensions. Example 3. The rotor of example 1 or 2, wherein the permanent magnet configuration of the first set (S1) is substantially V-shaped or linear, and the permanent magnet configuration of the second set (S2) is substantially U-shaped or V-shaped. Example 4. A rotor according to any of Examples 1 to 3, wherein the permanent magnet arrangement in each symmetrical portion (S2.1, S2.2) of the second set (S2) comprises first (M2.1, M2.3) and second (M2.2, M2.4) permanent magnets extending continuously along a first direction (D3) inclined with respect to the radially extending d-axis of symmetry (A) and a second direction (D4) inclined with respect to the first direction (D3), respectively, and wherein the two magnets of both symmetrical portions together form a U-shape. Example 5. The rotor of Example 4, wherein each inner flux barrier (44, 46) in the second set (S2) radially expands as it extends along the first direction (D3) from an adjacent first permanent magnet (M2.1, M2.3) toward a radially extending inner bridge (48, 50), and each inner flux barrier includes a radially aligned first outer end (44a) and an opposite second inner end (44b) at the expanding portion of each inner flux barrier, and the first outer end (44a) is closer to the outer edge (32) of the rotor than the second inner end (44b). Example 6. The rotor of Example 5, wherein the radially extending central flux barrier (52), separated from the second set of inner flux barriers (44, 46) by the two radially extending inner bridges (48, 50), extends a radial distance that is substantially the same as the radial distance between the first outer end (44a) and the opposite second inner end (44b) for each inner flux barrier. Example 7. The rotor of any one of Examples 4 to 6, wherein each outer flux barrier (40, 42) in the second set (S2) extends from the adjacent second permanent magnet (M2.2, M2.4) toward the outer edge (32) of the rotor along the second direction (D4) and terminates in an end (40b) including a side end (40b1) extending along the circumference of the rotor away from the first set (S1). Example 8. A rotor according to any one of Examples 1 to 7, wherein each symmetrical portion (S1.1, S1.2) in the first set (S1) has two opposite ends (60, 62, 64, 66), the outer ends (60, 64) terminating in an outer flux barrier (61, 65) of the flux barrier arrangement located near the outer edge (32) of the rotor. Example 9. The rotor of Example 8, wherein each outer flux barrier (61, 65) in the first set (S1) extends circumferentially in a nose-shaped configuration having a first side (61a) or nose bridge extending parallel to the outer edge (32) of the rotor from a first outer end (61b) or top of the nose to an opposite second outer end (61c) or tip of the nose, and a second side (61d) or nose bottom extending away from the outer edge (32) from the second end (61c) toward a third inner end (61e), wherein the second outer end (61c) is located farther from the permanent magnet arrangement than the first outer end (61b). Example 10. A rotor according to any of Examples 1 to 9, wherein the permanent magnet arrangement in each symmetrical portion (S1.1, S1.2) of the first set (S1) comprises permanent magnets (M1.1, M1.2) extending along a first direction (D1) inclined with respect to the radially extending d-axis of symmetry (A), and the permanent magnets (M1.1, M1.2) of both symmetrical portions together form a V-shape. Example 11. A rotor according to example 8 or 9 and example 10, wherein each outer flux barrier (61, 65) in the first set (S1) extends from the adjacent permanent magnet (M1.1, M1.2) towards the outer edge (32) of the rotor along a direction (D2) inclined with respect to the direction (D1) in which the adjacent permanent magnet extends. Example 12. The rotor of any one of Examples 8 to 11 when Example 10 depends on Example 8 or 9, wherein each symmetrical portion (S1.1, S1.2) in the first set (S1) has an inner end (62, 66) opposite the outer end (60, 64), and both inner ends (62, 66) are separated from each other by a radially extending bridge (70) aligned along the d-axis of symmetry (A). Example 13. The rotor of any one of Examples 8 to 12, when Example 10 depends on Example 8 or 9, wherein each outer flux barrier (61, 65, 40, 42) for each of the first and second sets (S1, S2) is not separated from the permanent magnet arrangement of the associated set. Example 14. The rotor of any one of Examples 8 to 13 when Example 10 depends on Example 8 or 9, wherein outer bridges (72, 74, 54, 56) are disposed between the outer edge (32) of the rotor and each outer flux barrier (61, 65, 40, 42) for each of the first and second sets (S1, S2), and each outer bridge (54, 56) of the second set extends a greater radial distance between the outer edge (32) of the rotor and each outer flux barrier (40, 42) than for each outer bridge (72, 74) of the first set. Example 15. An electric rotating machine (10) comprising a rotor (30) according to any one of Examples 1 to 14. Example 16. A vehicle comprising the electric rotating machine (10) of Example 15.

Claims

1. A rotor for an electric rotating machine configured to rotate about a longitudinal axis, the rotor including a plurality of magnetic poles arranged circumferentially relative to the rotor, each magnetic pole comprising at least a first set and a second set having a permanent magnet arrangement and a flux barrier arrangement, respectively; the first set being positioned near an outer edge of the rotor, and the second set being positioned farther from the outer edge in a radial direction relative to the longitudinal axis of the rotor than the first set; Each magnetic pole has the following configuration in a transverse cross section of the rotor relative to a longitudinal axis of the rotor: each of said first and second sets is symmetrical with respect to a d-axis of symmetry extending radially of said poles and comprises two symmetrical parts located on either side of said d-axis of symmetry; each symmetrical section in the second set has two opposite ends terminating respectively in an outer flux barrier of the flux barrier arrangement located near the outer edge of the rotor and in an inner flux barrier of the flux barrier arrangement located further from the outer edge than the outer flux barrier, the inner flux barriers of both symmetrical sections being separated from each other by an arrangement comprising two radially extending inner bridges flanked by a radially extending central flux barrier aligned along the d-axis of symmetry, each of the inner flux barriers includes an outer end extending radially outward from the rotor and an inner end extending radially inward from the rotor; the outer end and the inner end protrude outward beyond a width of an outer shape of the adjacent permanent magnet configuration of the second set, and the inner end protrudes further than the outer end; the central flux barrier is filled with resin; A rotor wherein each of the two radially extending inner bridges extends laterally in a direction perpendicular to the radial direction by a dimension in the range of 0.5 mm to 1.2 mm depending on the size of the rotor.

2. The rotor of claim 1 , wherein the permanent magnet configurations of the first set are substantially V-shaped or linear, and the permanent magnet configurations of the second set are substantially U-shaped or V-shaped.

3. 2. The rotor of claim 1, wherein the permanent magnet arrangement in each symmetrical portion of the second set includes first and second permanent magnets extending continuously along a first direction inclined with respect to the radially extending d-axis of symmetry and a second direction inclined with respect to the first direction, respectively, and the two permanent magnets in both symmetrical portions together form a U-shape.

4. 4. The rotor of claim 3, wherein each inner flux barrier in the second set flares radially as it extends along the first direction from an adjacent first permanent magnet toward a radially extending inner bridge, each inner flux barrier including a radially aligned first outer end and an opposite second inner end at the flared portion of each inner flux barrier, the first outer end being closer to the outer edge of the rotor than the second inner end.

5. 5. The rotor of claim 4, wherein the radially extending central flux barrier separated from the inner flux barriers of the second set by the two radially extending inner bridges extends a radial distance that is substantially the same as the radial distance between the first outer end and the opposite second inner end for each inner flux barrier.

6. 6. The rotor of claim 4, wherein each outer flux barrier in the second set extends along the second direction from an adjacent second permanent magnet towards the outer edge of the rotor and terminates at an end including a side end that extends along the circumference of the rotor away from the first set.

7. 2. The rotor of claim 1, wherein each symmetrical portion in the first set has two opposite ends, the outer ends terminating in an outer flux barrier of the flux barrier arrangement located near the outer edge of the rotor.

8. 8. The rotor of claim 7, wherein each outer flux barrier in the first set extends circumferentially in a nose-shaped configuration having a first side or nose bridge extending parallel to the outer edge of the rotor from a first outer end or top of a nose to a second outer end or tip opposite the nose, and a second side or nose bottom extending away from the outer edge from the second outer end toward a third inner end, the second outer end being located farther from the permanent magnet arrangement than the first outer end.

9. 9. A rotor as claimed in claim 7 or 8, wherein the permanent magnet arrangement in each symmetrical portion of the first set includes permanent magnets extending along a first direction that is inclined relative to the radially extending d-axis of symmetry, and the permanent magnets in both symmetrical portions together form a V-shape.

10. 10. The rotor of claim 9, wherein each outer flux barrier in the first set extends from an adjacent permanent magnet toward the outer edge of the rotor along a direction oblique to the first direction in which the adjacent permanent magnet extends.

11. 9. A rotor according to claim 7 or 8, wherein each symmetrical portion in the first set has an inner end opposite the outer end, the inner ends being separated from each other by a radially extending bridge aligned along the d-axis of symmetry.

12. A rotor according to claim 7 or 8, wherein each outer flux barrier for each of the first and second sets is not separated from the permanent magnet arrangement of the associated set.

13. 9. A rotor according to claim 7 or 8, wherein outer bridges are disposed between the outer edge of the rotor and each outer flux barrier for each of the first and second sets, each outer bridge of the second set extending a greater radial distance between the outer edge of the rotor and each outer flux barrier than for each outer bridge of the first set.

14. An electric rotating machine comprising a rotor according to claim 1 or 2.

15. A vehicle comprising the electric rotating machine of claim 14.

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