1005 results about "Cogging torque" patented technology

A magnetic gap is provided between a permanent magnet of a rotor and an auxiliary magnetic pole portion which is arranged adjacent to the permanent magnet in a peripheral direction. A gradual change in a magnetic flux density distribution of a surface of the rotor is obtained and a cogging torque and a torque pulsation are restrained. By obtaining a reluctance torque according to the auxiliary magnetic pole, a permanent magnet electric rotating machine in which the cogging torque and the torque pulsation are restrained can be obtained and further an electromotive vehicle having the permanent magnet electric rotating machine can be provided.

A rotor (10) for a rotary electric machine (1) comprises a rotation shaft (11), and a plurality of rotor cores (120-129) fixed to the rotation shaft (11) and axially split. The rotor cores (120-129) have outer peripheral surfaces (120A-129A) with a circular cross section. Permanent magnets (13) extending through the rotor cores (120-129) are arranged at equal circumferential intervals. Voids (120B-129B) extending axially through the rotor cores (120-129) are formed between the outer peripheral surfaces (120A-129A) and the permanent magnets (13). The voids (120B-129B) of two adjacent rotor cores (120-129) are formed at circumferentially different positions, thereby being capable of suppressing the cogging torque without introducing a reduction in output torque.

The present invention provides miniaturization of brushless motors and brush motors used in electric devices, a ring magnet which simultaneously achieves both high torque and a reduction in cogging torque, a ring magnet with yoke, and a brushless motor. The thin hybrid magnetized ring magnet of the present invention is structured of, in a ring magnet comprised of a plurality of magnetic poles, a radially magnetized main pole and an interface for which the interface of the adjoining main pole is polar anisotropic. When the thin hybrid magnetized ring magnet structured in this manner is applied to a brushless motor, in the case of radial magnetizing, the abrupt change in magnetic flux of the interface between the magnetic poles becomes smooth and cogging torque is greatly reduced due to polar anisotropic magnetization of the interface. At the same time, by polar anisotropically magnetizing the interface between the magnetic poles, magnetic flux is concentrated on the radially magnetized main pole, and in comparison to only radial magnetization, maximum surface magnetic flux improves and it is possible to attain high torque.

A permanent-magnet rotating machine includes a rotor having a rotor core carrying on its curved outer surface multiple permanent magnets arranged in two rows along an axial direction in such a manner that the permanent magnets in one row are skewed from those in the other row in a circumferential direction by a row-to-row skew angle (electrical angle) thetae, and a stator having a cylindrical stator core in which the rotor is disposed, the stator core being provided with stator coils for producing a rotating magnetic field for rotating the rotor. A lower limit of the row-to-row skew angle thetae is set at a value larger than 30 degrees (electrical angle). A cogging torque ratio, or the ratio of a cogging torque occurring in the absence of skew to a cogging torque occurring when the permanent magnets are skewed, at a row-to-row skew angle of 30 degrees is calculated based on the relationship between the cogging torque ratio and the row-to-row skew angle thetae and B-H curve properties of the stator core, and an upper limit of the row-to-row skew angle thetae is set at a value not larger than its maximum value at which the cogging torque ratio does not exceed the calculated cogging torque ratio at 30 degrees.

A brushless generator with permanent-magnet multi-pole rotor disks and stator winding disks in their axial magnetic field includes integral electronics to efficiently generate regulated DC current and voltage from mechanical input power over a broad speed range. All power for the electronics is provided by rectifier diodes from its stator windings. Differential amplifiers provide stator voltage feedback signals. Its power rating is scalable, depending on the number of its disks. Having no iron cores and no gears, it incurs no cogging torque, and no gear friction. Integral power control electronics includes high-frequency pulse-width-modulated boost regulation, which provides regulated current at requisite voltage over its broad speed range. A main wind-powered embodiment to produce DC power for a constant voltage DC load over a broad speed range includes signal processing so output power varies according to the third power of speed. Combined boost-regulation, zero cogging torque, and no gearing, enable a wide speed range, for better power quality and higher wind energy yields.

A cylindrical linear motor, an electromagnetic suspension, and a vehicle using the same, which can generate a large thrust and reduce torque pulsations and cogging torque. The cylindrical linear motor comprises a stator and a slider disposed with a gap left relative to the stator and being linearly movable relative to the stator. The stator comprises a stator core having stator salient poles, and 3-phase stator windings inserted in slots formed in the stator core. The slider comprises a plurality of permanent magnets fixed to a slider core. The motor satisfies τp:τs=9:9±1 where τs is a pitch of the stator salient poles and τp is a pitch of the permanent magnets.

A method and apparatus for reducing or eliminating the effects of torque ripple and cogging torque and otherwise improving performance in an electromechanical machine such as a motor or generator. The rotor and/or stator is conceptually sectionalized and the sections spaced apart by amount sufficient to alleviate deleterious aspects of cogging torque and torque ripple. Positioning of the stator teeth or rotor magnets is determined based on the calculated spacing. Conceptual sections may be formed as physically individual segments. Unwound teeth may be disposed in end spaces between sections occupying less than the entire area of the end space.

In a spindle motor, a core (33) includes a plurality of core plates (34), which are laminated one on another. The core (33) is constituted by laminating two cores, that is, a first core (34a) and a second core (34b), which are different from each other in shape of a surface facing to a rotor magnet (32). At least a part of a cogging torque generated at the second core (34b) can be cancelled by a cogging torque generated at the first core (34a).

A laminated body of a motor includes: a yoke part having a belt shape with a long length in comparison with its width and spirally laminated to form a hollow cylindrical shape; a plurality of teeth parts protruding from one side edge of the yoke part in a width direction and disposed along a longitudinal direction in an isolated manner at a predetermined distance; a stopping protrusion extendingly formed at a protruding end of the teeth part in a longitudinal direction of the yoke part; and an inclined portion having an inclined surface formed by decreasing a width of the stopping protrusion toward its end so as to reduce cogging torque, so that a minimum passage for a winding nozzle is provided while cogging torque is reduced. A laminated body of a motor includes: a yoke part having a belt shape with a long length in comparison with its width and spirally laminated to form a hollow cylindrical shape; a plurality of teeth parts protruding from one side edge of the yoke part in a width direction and disposed along a longitudinal direction in an isolated manner at a predetermined distance; and a protrusion receiving groove recessed in one side of the teeth part along a thickness direction and a coupling protrusion protruding from its other side along the thickness direction of the teeth part to be inserted and fixed by each other, so that defective measurement and an increase in production time caused by welding operation are prevented.

A permanent magnet electric motor 10 comprises a rotor 30 provided with two stages of permanent magnets in the axial direction on an outer circumferential face of a rotor iron core, and having a shaft shifted by a stage skew angle θr in electrical angle to decrease a first frequency component of cogging torque in the circumferential direction of the rotor iron core between two stages of the permanent magnets, a stator iron core 21 of cylindrical shape provided with the stator winding for producing a rotating magnetic field causing the rotor 30 to be rotated, and a stator 20 dividing the stator iron core 21 into plural blocks in the axial direction, and shifted by a stage skew angle θs in electrical angle to decrease a second frequency component of the cogging torque in the circumferential direction of the stator iron core 21.

A permanent magnet type magnetic pole core structure capable of minimizing the cogging torque for a rotating electric machine such as an electric motor or a power generator is disclosed. The rotating electric machine comprises: a magnetic pole core and an armature core. The magnetic pole core comprises a plurality of magnetic pole structures in a number of M, while each magnetic pole structure comprises at least one permanent magnet and can be used for defining two reference lines with an expanding angle sandwiched therebetween, and a periphery of the magnetic pole core enclosing the pole structure defining between the two reference lines is divided into a first arc surface, a second arc surface and a third arc surface. In an exemplary embodiment, the armature core comprises a plurality of slot structures in a number of S. The ratio of the amount of slot structure to the amount of the magnetic pole structure, i.e. S/M, is 3/2. With the aforesaid permanent magnet type magnetic pole core structure, the cogging torque of the rotating electric machine can be minimized.

A permanent magnet motor is provided. The permanent magnet motor includes a stator having a stator shaft having an outer surface, K salient teeth formed upon the outer surface, and K winding slots formed among the K salient teeth, and a rotor having a first inner surface facing the outer surface, and P pairs of permanent magnets formed on the first inner surface, each of which has a second inner surface facing the outer surface and at least a groove formed on the second inner surface to reduce a cogging torque.

The invention discloses an application method of mixed permanent magnets in a flux-switching permanent magnet motor, and relates to stator-core motors with permanent magnets. Rare-earth permanent magnets with high magnetic energy products are mounted at yoke positions of a stator module of the flux-switching permanent magnet motor. Ferrite permanent magnets with low magnetic energy products are mounted at tooth positions close to the motor stator module. The rare-earth permanent magnets with the high magnetic energy products and the ferrite permanent magnets with the low magnetic energy products are connected to be integrated into the mixed permanent magnets. The mixed permanent magnets with clockwise magnetization directions are mounted on one side of the motor stator module. The mixed permanent magnets with anticlockwise magnetization directions are mounted on the other side of the motor stator module. The mixed permanent magnets with the clockwise magnetization directions and the mixed permanent magnets with the anticlockwise magnetization directions are alternately mounted on two sides of the motor stator module. The defects of ultrahigh cost of existing flux-switching permanent magnet motors, serious magnetic saturation of teeth, reduction of motor torque density and large cogging torque are overcome.

There is provided an interior permanent magnet rotary motor that can reduce cogging torque and can also reduce the amount of permanent magnet used, without reducing torque.

In an interior permanent magnet rotary motor of the present invention having N slots 6 and P permanent magnet magnetic pole sections 11, in which P/N is set in the range of ⅔ to 43/45 and Po in a irreducible fraction Po/No of the P/N is set to be an odd number, an pole arc ratio ψ_p is defined to be the ratio of θpp/θp where an angle between two line segments assumed for a pair of flux barriers 21, each of which connects the center of a rotor core and one of a plurality of corners of the section of each flux barrier that is closest to the surface of the rotor core 9 is indicated by the θpp and an angle obtained by dividing the full circumference angle (360°) of the rotor core by the number of the permanent magnet pole sections is indicated by the θp. Then, the pole arc ratio indicated by Ψ_p is determined is so as to satisfy the relation of Ψ_p=2mP/N+P/4LCM (P, N)−2n, in which LCM (P, N) is the least common multiple between P and N, m and n are arbitrary natural numbers, and the Ψ_p is larger than zero but smaller than one.

A rotor of a rotating electrical machine is provided in which neither deterioration nor fluctuation in the cogging torque is caused and that causes neither physical enlargement nor cost increase. The rotor of a rotating electrical machine, provided with a plurality of magnetic poles 3 that are fixed on a rotor iron core 2 and arranged spaced apart from one another in the circumferential direction of the rotor iron core 2, is characterized by including a tube-shaped non-magnetic ring 4 mounted on the outer circumferential surfaces of the plurality of magnetic poles 3, and characterized in that the non-magnetic ring has a plurality of inner-diameter bulging portions 41 that abut on the corresponding outer circumferential surfaces of the plurality of magnetic poles.

In the prior art in which permanent magnets are regularly arranged over the whole circumference of a rotor core, a satisfactory magnetic flux distribution is hard to obtain, and the cogging torque and the distortion factor of the induced electromotive force waveform are large, whereby characteristics of a rotating electric machine are poor. Also, because the permanent magnets are arranged over the whole circumference, a large number of permanent magnets are required and cost reduction is difficult. A permanent magnet rotating electric-machine of the invention comprises a stator provided with a plurality of windings, and a rotor in which magnets are disposed in slots formed in a rotor core along an outer circumference thereof, the rotor core being fixed on a rotary shaft rotating inside the stator, and in which one magnetic pole is constituted by each group of three or more of the magnets. A total angle occupied by the group of magnets constituting one magnetic pole is in the range of 150 to 165 degrees in terms of an electrical angle.

An electric motor has a rotor (36) and a stator (28) having a lamination stack formed with slots (126). The slots have a predetermined slot pitch (τ_S), and a multi-phase stator winding is arranged in them. The rotor (36) has salient poles having pole shoes (136) and a magnetic return path (130). Between the return path (130) and each pole shoe (136), a recess (138, 140) is formed for receiving a permanent magnet (38). On each side of such a permanent magnet (38), a region (146a, 146b) of poor magnetic conductivity is arranged, in order to make the flux distribution in the air gap more sinusoidal. Measuring in a circumferential direction, the width (β) of a pole shoe (136) decreases with increasing distance from an interface (138) between said return path and said permanent magnet (38), and, at a place of lowest width, the pole shoe has an angular extent (β_C)which has, with respect to the slot pitch (τ_S) between said stator slots (126), the following relationship:

β_C=n*τ_S*(1−0.02) . . . n*τ_S*(1−0.2),

where n=1, 2, 3 . . . and

β_C and τ_S are measured in mechanical degrees.

A permanent magnet electric machine includes a stator with salient stator poles. A rotor includes two or more axial rotor sections that are rotationally offset by an offset angle equal to the cogging angle divided by the number of axial rotor sections. The axial rotor sections include rotor poles with permanent magnets. In one embodiment, the permanent magnet electric machine has a 12/10 slot/pole combination. The permanent magnets have a magnet dimension angle between 31 and 35 degrees. An air gap ratio of the electric machine is between 1.35 and 2.5. A slot opening ratio of the electric machine is less than or equal to one. In another embodiment, the permanent magnet electric machine has an 18/12 slot/pole combination. The permanent magnets have a magnet dimension angle that is between 25 and 28 degrees. An air gap ratio of the electric machine is between 1.35 and 2.5. A slot opening ratio of the electric machine is less than or equal to one.