Chang-Chou Hwang

Reduction of cogging torque in spindle motors for CD-ROM drive

In this paper an approach to design a low cogging torque spindle motor without skewing stator slots or magnet poles is proposed. The effects of the slot and pole number combination and optimal choice of the width ratio of armature teeth to magnet pole are are investigated. A finite element method based on a combination of electromagnetic field and circuit equations for magnetic field modeling and torque prediction is presented. Results show that increasing the number of the least common multiple of slot and pole gives only sufficient conditions to decrease the level of cogging torque. To obtain smaller amplitude of the cogging torque, it is also necessary to choose the width ratio of armature teeth to magnet pole are properly.

Optimal Design of an SPM Motor Using Genetic Algorithms and Taguchi Method

This paper presents the use of genetic algorithms (GAs) and the Taguchi method in optimizing an surface-mounted permanent magnet (SPM) motor for use as a fan motor in air-conditioners. GAs were used to optimize the efficiency of the motor, and the Taguchi optimization method was used and the finite-element method (FEM) analysis was conducted to compute the performance of the motor design generated by the Taguchi design of experiments.

Effects of leakage flux on magnetic fields of interior permanent magnet synchronous motors

This paper presents a magnetic circuit model for an interior permanent magnet (IPM) synchronous machine. The model includes each portion of magnetic flux paths, especially the leakage flux paths around the magnets in the rotor. The magnetic field quantities are expressed analytically in terms of the reluctance ratio /spl beta/ and the leakage flux ratios /spl eta/ and /spl lambda/. It is shown that the width and the iron saturation level of the iron bridge have an important effect on the magnetic field distribution within the motor. Numerical results confirm the validity of the analytical model.

Optimal Design of a Permanent Magnet Linear Synchronous Motor With Low Cogging Force

In this paper, a technique for reducing the cogging force in slotted permanent magnet linear synchronous motors (PMLSMs) is presented. A two-step minimization process that depends on the slotting and end effects is proposed. Taguchis parameter method, coupled with 2-D and 3-D finite element analysis (FEA), is employed to minimize the cogging force.

Optimization for Reduction of Torque Ripple in an Axial Flux Permanent Magnet Machine

This paper presents an axial-flux permanent magnet (AFPM) machine with an internal coreless stator and twin external permanent magnet (PM) rotors, based on the finite-element method (FEM) by robust design, call Taguchi method to the optimum design for minimum the torque ripple and maximum the ratio between torque ripple and average torque. The optimization is realized by analyses and simulations with finite-element analysis (FEA). The design optimization process is described and the results are presented in this paper.

Magnetic Sensor Based on Side-Polished Fiber Bragg Grating Coated With Iron Film

This paper presents a novel fiber-optic magnetic sensor based on a side-polished fiber Bragg grating coated with thin iron film. The Bragg wavelength shift of 0.08 nm was measured at the distance of 0.38 mm between fiber sensor and Nd-Fe-B magnet with remanent flux density of 1.115 T. We demonstrate the ability to measure magnetic fields using such a device

Design of high-performance spindle motors with concentrated windings

This paper describes a method for the design of high-performance permanent magnet (PM) spindle motors with concentrated windings. First, to design a low-cogging torque machine, a high least-common multiple of the pole and slot combination is selected. A winding layout procedure is presented. Three winding arrangements for the spindle motor with an eight-pole/nine-slot configuration are investigated. A comparison of the performance of the three winding arrangements is made using finite-element analysis. It provides a useful reference to be considered in the motor design.

Optimal Design of a High Speed SPM Motor for Machine Tool Applications

This paper deals with the optimal design of surface-mounted permanent magnet motors for use in a high speed spindle machine tool in glass grinding applications. We apply the Taguchi method to refine the stator structure and use segmented rotor magnets for the motor to yield the desired performance. A thermal analysis is conducted to obtain the temperature distribution within the motor. We examine the results using finite element analysis and validate them by experimental measurements.

Design Assessments of a Magnetic-Geared Double-Rotor Permanent Magnet Generator

By adopting the double-rotor structure and the coaxial magnetic gear concept, a permanent magnet (PM) generator is proposed for harvesting the wind energy directly without mechanical conversions. In addition to the physical model realizations, this paper will present the detailed design and implementation concerns of the magnetic-geared double-rotor PM generator along with thorough loss assessments. The comparisons of PM magnetization directions and arrangements, the selections of proper windings, and the operational efficiencies of this machine along with the terminal voltage phase shifts due to different loading conditions will all be summarized. The realization process of a portable 2.5-kVA generator that can be directly coupled to the mechanical driven source without additional mechanical gears will be demonstrated, and the feasibility of such a machine structure can certainly be confirmed from the satisfactory performance results.

Design and Analysis of a Novel Hybrid Excited Linear Flux Switching Permanent Magnet Motor

A hybrid excited linear flux switching permanent magnet motor (HLFSPMM) is a possible solution for developing a rare-earth-magnet-free electric motor with high force density. We designed an HLFSPMM that uses a ferrite magnet in place of a rare earth magnet. A suitable mover slot and stator pole number combination was selected in the initial design stage to achieve the desired performance capability. Structural refinements using design sensitivity analysis (DSA) based on the finite element method (FEM) were performed to enhance the machine performance. Simulation results have been validated by experimental measurements.