Electric motor capable of reducing cogging torque

a technology of electric motors and torques, applied in the direction of magnetic circuit rotating parts, magnetic circuit shapes/forms/construction, instruments, etc., can solve the problem of inability to adjust the magnitude of cogging torque to an arbitrary magnitud

Inactive Publication Date: 2015-04-16
FANUC LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to an electric motor with improved performance. The motor includes a rotor with magnetic pole units and a stator with slots facing the outer surface of the rotor. The magnetic pole units are shaped to generate a sine wave shape, and a concave or convex part is formed at the central part in the outer surface of each unit to prevent changes in cogging torque. This design ensures smooth operation of the electric motor without any fluctuations in performance.

Problems solved by technology

The electric motor described in JP2003-023740A is configured to reduce the magnitude of cogging torque by half, by substantially doubling the number of magnetic poles, but is unable to adjust the magnitude of the cogging torque to an arbitrary magnitude.

Method used

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  • Electric motor capable of reducing cogging torque
  • Electric motor capable of reducing cogging torque
  • Electric motor capable of reducing cogging torque

Examples

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Embodiment Construction

[0033]Hereinafter, the embodiments of the present invention will be described referring to FIGS. 1 to 21. FIG. 1 is a sectional view schematically illustrating an internal configuration of an electric motor 100 according to an embodiment of the present invention. The electric motor 100, which is a permanent magnet synchronous electric motor with eight poles and twelve slots, includes a rotor 1 provided with permanent magnets 3 and a stator 2 disposed around the rotor 1. An output shaft 4 is disposed at a center of the rotor 1.

[0034]Predetermined space is formed between an outer peripheral surface 11 of the rotor 1 and an inner peripheral surface 21 of the stator 2. In the inner peripheral surface 21 of the stator 2, slot openings 22 and teeth 23 are alternately formed in a circumferential direction. Slots 20 are formed on radial direction outsides of the slot openings 22. A coil is received in each slot 20. By supplying current to the coil, the stator 2 forms a rotating magnetic fie...

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Abstract

An electric motor including a rotor including magnetic pole units and a stator including slots facing an outer peripheral surface of the rotor. Each of the magnetic pole units is bulged to an outside in a radial direction so that a waveform of a magnetic flux density generated from the rotor is a sine wave shape, and a concave part or convex part which is small enough to prevent changing of a waveform cycle of cogging torque determined by a least common multiple of the number of slots and the number of magnetic poles of the rotor, is formed at a central part in a circumferential direction of an outer peripheral surface in each of the magnetic pole units.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an electric motor capable of reducing cogging torque.[0003]2. Description of the Related Art[0004]In a permanent magnet electric motor that includes a rotor having a permanent magnet, due to the presence of slots of a stator core facing an outer peripheral surface of the rotor, magnetic coenergy fluctuates during rotation of the rotor, and therefore generates cogging torque that is torque pulsation. The cogging torque is preferably reduced because the cogging torque interferes with smooth rotation of the rotor to generate sound or vibration. Conventionally, as an electric motor designed to reduce such cogging torque, there are known electric motors as described in Japanese Laid-open Patent Publication No. 2003-023740 (JP2003-023740A) and Japanese Laid-open Patent Publication No. 11-164501 (JP11-164501A).[0005]A rotor of an electric motor described in JP2003-023740A includes a magnetic po...

Claims

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Application Information

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IPC IPC(8): H02K1/24H02K1/16
CPCH02K1/24H02K1/16H02K29/03H02K1/2773H02K1/2706H02K2213/03A61B3/0025A61B3/102A61B5/0066A61B2562/0233A61B2576/00G01B9/02044G01B9/02084G01B9/02091
InventorMAEDA, TAKUYA
OwnerFANUC LTD