Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K1/00—Details of the magnetic circuit
  • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
  • H02K1/22—Rotating parts of the magnetic circuit
  • H02K1/27—Rotor cores with permanent magnets
  • H02K1/2706—Inner rotors
  • H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
  • H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
  • H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
  • H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
  • H02K1/2766—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM] having a flux concentration effect
  • H02K1/2773—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM] having a flux concentration effect consisting of tangentially magnetized radial magnets
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K1/00—Details of the magnetic circuit
  • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
  • H02K1/22—Rotating parts of the magnetic circuit
  • H02K1/27—Rotor cores with permanent magnets
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K1/00—Details of the magnetic circuit
  • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
  • H02K1/22—Rotating parts of the magnetic circuit
  • H02K1/27—Rotor cores with permanent magnets
  • H02K1/2706—Inner rotors
  • H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
  • H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
  • H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
  • H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K2213/00—Specific aspects, not otherwise provided for and not covered by codes H02K2201/00 - H02K2211/00
  • H02K2213/03—Machines characterised by numerical values, ranges, mathematical expressions or similar information

Definitions

• the present invention relates to a permanent magnet rotor for a rotating electrical machine.
• the invention also relates to a rotary electric machine comprising a rotor of this type, in particular for applications such as an electric traction motor or an accessory motor in electric and hybrid motor vehicles.
• “Mild-hybrid” applications generally relate to electrical machines of the order of 8 to 20 kW, for example, an electric motor mounted on the front face of a heat engine and coupled thereto by a transmission belt. It is possible with such an electric motor to reduce the displacement of the engine (“engine downsizing" in English terminology) by providing a power assisted torque that provides additional power, especially during rework. In addition, a low-speed traction, for example in urban environment, can also be provided by the same electric motor.
• “Full-hybrid” type applications generally concern motors from 30 to 50 kW for series and / or parallel type architectures with a more advanced integration level of the electric motor or motors in the vehicle's power train.
• Neodymium-Iron-Boron Neodymium-Iron-Boron
• SmFe Samarium-Iron
• SmCo Samarium-Cobalt
• rare earth magnets in an electric machine rotor for automotive applications are no longer economically viable, and probably not sustainable, the other term of the alternative is constituted by magnets based on ferrites.
• the object of the present invention is therefore to optimize the volume of the magnets of a rotor to maximize the efficiency of the machine while respecting specified dimensional and mechanical constraints. It relates specifically to a rotary electric machine rotor comprising a plurality of alternating North poles and South poles and formed from a plurality of permanent magnets arranged in first recesses.
• first recesses extend axially and are evenly distributed between a circumferential portion and a central portion of the magnetic mass of the rotor so as to define a plurality of circumferential pole sections.
• the permanent magnets of the rotor type in question have a polygonal radial section.
• the radial section of the permanent magnets comprises a substantially rectangular portion close to the circumferential portion adjacent to a substantially trapezoidal portion close to the central portion with a ratio R of a first height h of the trapezoidal portion to a second height H of the rectangular portion, in a radial direction, which is between 0.25 and 0.70 and is predetermined so as to maximize the efficiency of said electric machine.
• Each of the polar sections of the rotor according to the invention is preferably held radially by a central tongue extending axially and forming a partition between two of the first consecutive recesses.
• a width L of the rectangular part, in a circumferential direction, is predetermined so as to maximize the volume of each of the permanent magnets in a limit ⁇ 0 of the mechanical stresses ⁇ supported by this tab during operation of the machine.
• the ratio of the heights h / H characterizing the section of the magnets is limited higher according to a predetermined minimum thickness E of the tongue in the same limit ⁇ 0 mechanical stresses ⁇ supported by it.
• the permanent magnets of the rotary electric machine rotor according to the invention are made of ferrite.
• the rotor according to the invention further comprises a plurality of second recesses which extend axially and which are arranged between the permanent magnets in an intermediate portion of the rotor between the central portion and the circumferential portion.
• the part circumferential rotor is open radially, at least partially, facing the permanent magnets.
• the invention also relates to a rotating electrical machine which comprises a rotor having the above characteristics.
• Figure 1 shows a simplified radial sectional view of a permanent magnet rotor according to the invention.
• FIG. 2 shows the variation of the stator current of an electrical machine comprising a permanent magnet rotor of the type of that of the invention as a function of the ratio of heights characterizing a radial section of these permanent magnets for a constant motor torque.
• FIG. 3 shows the variation of the mechanical stresses supported during operation by a tongue now radially maintaining a pole section of the permanent magnet rotor of the type of that of the invention as a function of the height ratio characterizing a radial section of these permanent magnets for a constant motor torque.
• FIG. 1 The simplified radial section of a rotor 1 with permanent magnets in the preferred embodiments of the invention, shown in FIG. 1, clearly shows the arrangement in the magnetic mass 2 of the permanent magnets 3 in first regularly distributed recesses 4 between a circumferential portion 5 and a central portion 6 so as to form a plurality of North N poles and South poles S alternate.
• a concrete embodiment of a machine comprising such a rotor is for example a motor / generator of 8 to 20 KW for applications in motor vehicles of the so-called "mild-hybrid" type.
• this machine In its motor mode of operation this machine can be designed for the start of the engine, assistance in torque of the engine and for low-speed electric traction of the vehicle.
• a rotor 1 having ten permanent magnets 3 rotates inside a stator (not shown) having a plurality of notches.
• the stator and the rotor 1 are made conventionally with packets of metal sheets forming magnetic masses 2.
• the notches of the stator are provided to receive stator windings (not shown) and form between them a plurality of stator teeth. According to the embodiments, the notches will be provided for housing concentrated windings, wound on large teeth, or distributed windings.
• stator windings are traversed by a stator current and create a rotating magnetic field driving the rotor 1.
• the engine torque supplied depends in particular on the intensity of the stator current Is and the magnetic flux in the rotor 1.
• the volume of the ferrite magnets must be optimized.
• the flux concentration rotors known from the state of the art generally comprise magnetized bars of rectangular cross section arranged in equiangular axial planes.
• a width, in a circumferential direction, of a bar is limited by a length of the chord of a circular sector of a central part of the rotor, while the bar occupies only a small part of the magnetic mass in the circumferential part.
• the invention therefore proposes to give a portion of the magnet 3 close to the central portion 6 of the rotor 1 a wedge shape.
• a radial section of a magnet 3 in the rotor 1 has a substantially trapezoidal portion 7 close to the central portion of the rotor 1 and a substantially rectangular portion 8 near the circumferential portion 5.
• Figure 2 shows the stator current Is necessary to obtain the same motor torque as a function of this ratio R of the heights h / H for a test machine.
• the sides of the substantially trapezoidal portion 7 of the section of the magnets 3 are located in planes parallel to the axial planes of the rotor 1 (the large base and the small base being substantially located in planes parallel to a plane tangential to the rotor 1).
• the first recesses 4 containing the magnets 3 are therefore separated by central tabs 9 forming partitions having a thickness E which is chosen to be of low value in order to minimize flux leakage by the central part 6 of the rotor.
• the thickness E is constant, but it will be noted that it may be variable in certain embodiments.
• a width L of the magnets 3 and the thickness E of the tongues 9 are two parameters varying in opposite directions for geometrical reasons. The width L is thus increased so as to maximize the volume of the magnets 3 as long as the thickness E of the tongues is sufficient to enable them to withstand the mechanical stresses ⁇ .
• the ratio R of the heights h / H influences the level of the mechanical stresses ⁇ supported by a tongue 9 as shown in FIG. 3.
• the rotor 1 according to the invention advantageously comprises a plurality of second recesses 11 arranged in the polar sections 10, as shown in FIG. 1.
• these second recesses 11 decrease the mass of the polar sections 10, and consequently reduce the mechanical stresses ⁇ supple by the tongues 9 due to these polar sections 10, which makes it possible to increase the mass of the magnets 3.
• the first recesses 4 of the rotor 1 according to the invention preferably comprise openings 12 towards the periphery of the magnetic mass 2.
• openings have the effect of increasing the reluctance of these parts of the magnetic circuit, and therefore of limiting the leakage flux of the magnets 3, while also contributing to the decrease in the mass of the circumferential portion 5 of the rotor 1, which makes it possible to increase the mass of the magnets 3 while remaining within the same limit at 0 of the mechanical stresses supported by the tongues 9.
• magnets 3 having a radial section comprising a rectangular portion 8 and a trapezoidal portion 7 advantageously consist of two juxtaposed bars, one having a rectangular cross section and the second having a trapezoidal cross section.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Permanent Field Magnets Of Synchronous Machinery (AREA)
• Iron Core Of Rotating Electric Machines (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=47116056

Family Applications (1)

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• 2011
  • 2011-10-27 FR FR1159760A patent/FR2982093B1/fr active Active
• 2012
  • 2012-10-08 EP EP12780226.2A patent/EP2771962A2/fr active Pending
  • 2012-10-08 KR KR1020147011082A patent/KR20140094516A/ko not_active Application Discontinuation
  • 2012-10-08 JP JP2014537685A patent/JP6211524B2/ja active Active
  • 2012-10-08 US US14/354,732 patent/US9716410B2/en active Active
  • 2012-10-08 CN CN201280052641.0A patent/CN103891105B/zh active Active
  • 2012-10-08 WO PCT/FR2012/052273 patent/WO2013060960A2/fr active Application Filing

Non-Patent Citations (2)

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