Abstract
In multi-pole permanent magnets (PMs) such a ring-type PMs, as multi-poles are magnetized in one segment, the ends of each pole are weakly magnetized, which is known as the dead zone. Thus, when analyzing characteristics of the motor with multi-pole PMs, accurate results can be obtained by considering the magnetization distribution. For this reason, this paper proposed an equivalent magnetic circuit (EMC) for external-rotor surface-mounted permanent magnet synchronous motors (SPMSMs) considering the dead zone to analyze the effects of the dead zone on the characteristics of the motor. As the magnetization in the dead zone gradually decreases toward the end of the pole, the magnetization distribution is assumed to have a trapezoidal shape. To describe the magnetization distribution, each pole was divided into several elements, and the equivalent residual magnetic flux density was applied to the elements of the dead zone. Finally, the validity of the proposed EMC was verified by comparing the back electro-motive force and air-gap magnetic flux density obtained by the EMC, finite-element analysis, and test.
Highlights
IntroductionPermanent magnet synchronous motors (PMSMs) are widely used for industrial and household applications due to their high power density, torque density, and efficiency [1,2,3,4,5]
Permanent magnet synchronous motors (PMSMs) are widely used for industrial and household applications due to their high power density, torque density, and efficiency [1,2,3,4,5].Among them, as surface-mounted PMSMs (SPMSMs) generally have a smaller cogging torque, torque ripple, and vibration than interior permanent magnet synchronous motors (IPMSMs) do, they are widely used for robot applications that require precise control or as a motor for home appliances requiring low noise and vibration characteristics [6,7]
The no-load and load characteristics of the surface-mounted permanent magnet synchronous motors (SPMSMs) according to the dead zone angle were calculated and analyzed using the proposed equivalent magnetic circuit (EMC), and the results were compared with Finite element element analysis analysis (FEA)
Summary
Permanent magnet synchronous motors (PMSMs) are widely used for industrial and household applications due to their high power density, torque density, and efficiency [1,2,3,4,5]. The no-load and load characteristics of the SPMSM according to the dead zone angle were calculated and analyzed using the proposed EMC, and the results were compared with FEA. Nm which a large differThis difference in cogging torque occurred because the no-load air-gap magnetic flux ence This difference in cogging torque occurred because the no-load air-gap magnetic changes according to the dead zone angle. 2b that the time flux changes according to the dead zone angle
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