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With the recent increase in the demand for convenient handheld home appliances, the quietness, power density, and weight of motors have been extensively studied. To this end, this article proposes a separated teeth motor (STM) with improved weight reduction and higher productivity than those of existing hair dryer motors. To reduce the weight of the stator, which possesses a high weight specificity in the motor, an STM model was designed with divided teeth to facilitate reduced iron consumption. Using this model, improvements in the production and performance of STM motors are proposed. For example, the workability of the motor is increased for the same torque; moreover, manufacture of compact and lightweight STMs is deemed possible. In addition, a reduction in torque ripple, cogging torque, and total harmonic distortion has been demonstrated via a finite-element method.

A surface permanent magnet synchronous motor (SPMSM) using ferrite magnet represents small air gaps and high stack lengths relatively. Thus, it has small edge effects on the performance of the motor, and a 2-D finite-element analysis (FEA) method is largely used to design it. In the case of the demagnetization analysis in the SPMSM, however, it is difficult to neglect fringing effects in air gaps, because the permeability of the permanent magnet is the same as air and the direction of the armature reaction is opposite to the magnetization direction. Therefore, the accuracy of the 2-D FEA is significantly degraded. In this paper, the edge effect of SPMSM on the demagnetization analysis is analyzed. For achieving it, the opposing magnetic field that contributes to the demagnetization is analyzed by two different elements, such as permanent magnet and armature reaction. In addition, a simplification model of the ${ {yz}}$ plane that can consider the edge effect is proposed to increase the accuracy of the conventional 2-D FEA, which is analyzed on the ${ {xy}}$ plane, and correction factors are also induced. Finally, its validity is verified by applying the proposed method to the conventional motors.

This paper presents the control method that inverter output keeps to linear to reference voltage of Synchronous Reluctance Motor (SynRM) using DC Link voltage Synthesis. This method is reduced torque ripple considering parameters with magnetic saturation. To estimate parameters of inductances for SynRM, the proposed method uses recursive least square (RLS) estimation algorithm. The estimated inductances are used for calculating torque and DC link voltage. The Inverter output voltage cannot be displayed to linear about inverter reference voltage if Real DC Link voltage is different from DC Link voltage of PWM amplitude. Also, the over-modulation is linearity broken if reference voltage is out of range. Torque ripple generates the vibration and noise of a motor. This paper proposes the control method so that the torque ripple decreases and the linearity of inverter output keeps using the DC Link voltage Synthesis. The proposed control method is verified by computer simulation and experiment.

This paper presents the design process of permanent magnets to enable a wide range of constant-power operation and reduce the torque ripple by using analytical and numerical methods in PMA-SynRM. For a wide range of constant-power operation, the minimum d-axis flux-linkage of the permanent magnet is designed to be close to zero. Moreover, the unbalanced flux density in each segment is adjusted by changing the size of each permanent magnet to reduce the torque ripple. Finally, control simulations and experiments will be conducted to prove the validity of the suggested process.

This paper presents a method to reduce torque ripple considering parameters with magnetic saturation. To estimate parameters of inductances for interior permanent magnet synchronous motor (IPMSM), the proposed method uses recursive least square (RLS) estimation algorithm. The estimated inductances are used for calculating torque and DC link voltage. Using the torque and the DC link voltage estimators, this control method can reduce torque ripple of IPMSM because of keeping linearity of inverter output. Therefore, the torque control system can achieve precise torque control. The proposed control method is verified by computer simulation and experiment.

This paper shows a study on the demagnetization performance analysis of permanent magnet according to three kinds of rotor types of an interior permanent magnet synchronous motor (IPMSM). It is very important to consider demagnetization performance as well as motor performance such as rated torque, output current, and efficiency when designing IPMSM. Three kinds of rotor types according to permanent magnet arrangement; single layer type, v shape type, and double layer type are generally used for IPMSM. In the paper, the magnetic equivalent circuits according to each rotor type are proposed in order for initial design of thickness of permanent magnets considering demagnetization by lumped constant related to magnetic circuit. The volume of permanent magnets per pole and back EMF of each rotor type is assumed to equal for the comparison of demagnetization of IPMSMs with same performance each other. Next, distribution of demagnetization in the permanent magnet is analyzed by using finite element method (FEM) for the verification of the results by magnetic equivalent circuit.

This paper presents the novel method inductance calculation of a synchronous reluctance motor (SynRM). Synchronous inductances (Ld and Lq) are exceedingly important factor of SynRM to drive. Because of self axis current as well as the other axis current, inductances of d-axis and q-axis of SynRM are varied. Using an equivalent circuit model for expressing d-axis and q-axis inductance variation, the authors elicit suitable equation considering iron loss and cross magnetic saturation. Parameters of motor to use calculation are gained by AC signal test.