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-This paper presents the implementation and characteristic analysis of a drive system for a three-phase permanent magnet motor with independent excitation winding that is applicable for electric bicycles. The design features improves the phase current waveform, output power, and torque by using advance angle control. This adjusts the phase angle of each phase current in relation to back EMF. In addition, a DC-side PI current control is performed through PWM generation circuit using a low-cost one-chip microcontroller and a CPLD chip, resulting in reduced system costs. Finally, the validity of this control scheme for driving electric bicycles and output/torque improvement characteristics are verified through analysis and experimental results.

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This paper presents a reduction method of vibration based on decreased cogging torque for interior type permanent magnet motor. The vibration source which affects biggest in the vibration of the interior type permanent magnet motor is the force, cogging torque, of the radius direction in compliance with a magnetic energy from between stator and the rotor. The notch is established in the rotor because notch could be applied most easily to the interior type permanent magnet motor and maximizes a reduction effect of cogging torque. The prototype machine was produced to estimate the vibration reduction by decreasing the cogging torque. The measured result is estimated among several frequencies.

This paper relates to a vibration analysis of brushless dc (BLDC) motors using the asymmetrical Z-axis overhang of permanent magnet. In BLDC motor, the asymmetrical Z-axis overhang of permanent magnet generates Z-axis thrust which leads to Z-axis eccentric force by commutated current on the rated load and then the Z-axis vibration. The Z-axis thrust ripple, the source of Z-axis vibration under commutated current, is analyzed by using 3-Dimensional Finite Element Method (3-D FEM), and the phenomena of Z-axis vibration is analyzed by experimentation.Index Term ⎯ Permanent magnet overhang, 3-D FEM, Z-axis thrust, Vibration. I.0197-2618/07/$25.00

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